2.
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Table 1: Evidence Categories | ||
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Evidence Category | Sources of Evidence | Definition |
A | Randomized controlled trials (rich body of data) | Evidence is from endpoints of well-designed RCTs (or trials that depart only minimally from randomization) that provide a consistent pattern of findings in the population for which the recommendation is made. Category A therefore requires substantial numbers of studies involving substantial numbers of participants. |
B | Randomized controlled trials (limited body of data) | Evidence is from endpoints of intervention studies that include only a limited number of RCTs, post hoc or subgroup analysis of RCTs, or meta-analysis of RCTs. In general, Category B pertains when few randomized trials exist, they are small in size, and the trial results are somewhat inconsistent, or the trials were undertaken in a population that differs from the target population of the recommendation. |
C | Nonrandomized trials Observational studies | Evidence is from outcomes of uncontrolled or nonrandomized trials or from observational studies. |
D | Panel Consensus Judgment | Expert judgment is based on the panel’s synthesis of evidence from experimental research described in the literature and/or derived from the consensus of panel members based on clinical experience or knowledge that does not meet the above-listed criteria. This category is used only in cases where the provision of some guidance was deemed valuable but an adequately compelling clinical literature addressing the subject of the recommendation was deemed insufficient to justify placement in one of the other categories (A through C). |
A variety of effective options exist for the management of overweight and obese patients, including dietary therapy approaches such as low-calorie diets and lower-fat diets; altering physical activity patterns; behavior therapy techniques; pharmacotherapy*; surgery; and combinations of these techniques.
Clinical GuidelinesTreatment of the overweight or obese patient is a two-step process: assessment and treatment management. Assessment requires determination of the degree of overweight and overall risk status. Management includes both reducing excess body weight and instituting other measures to control accompanying risk factors. AssessmentWhen assessing a patient for risk status and as a candidate for weight loss therapy, consider the patient's BMI, waist circumference, and overall risk status. Consideration also needs to be given to the patient's motivation to lose weight. Body mass indexThe BMI, which describes relative weight for height, is significantly correlated with total body fat content. The BMI should be used to assess overweight and obesity and to monitor changes in body weight. In addition, measurements of body weight alone can be used to determine efficacy of weight loss therapy. BMI is calculated as weight (kg)/height squared (m2). To estimate BMI using pounds and inches, use: [weight (pounds)/height (inches)2] x 703. Weight classifications by BMI, selected for use in this report, are shown in Table 2. A conversion table of heights and weights resulting in selected BMI units is provided in Table 3. Waist circumferenceThe presence of excess fat in the abdomen out of proportion to total body fat is an independent predictor of risk factors and morbidity. Waist circumference is positively correlated with abdominal fat content. It provides a clinically acceptable measurement for assessing a patient's abdominal fat content before and during weight loss treatment. The sex-specific cutoffs noted on the next page can be used to identify increased relative risk for the development of obesity-associated risk factors in most adults with a BMI of 25 to 34.9 kg/m2: * As of September 1997, the Food and Drug Administration (FDA) requested the voluntary withdrawal from the market of dexfenfluramine and fenfluramine due to a reported association between valvular heart disease and the use of dexfenfluramine or enfluramine alone or combined with phentermine. The use of these drugs for weight reduction, therefore, is not recommended in this report. Sibutramine is approved by FDA for long-term use. It has limited but definite effects on weight loss and can facilitate weight loss maintenance (Note: FDA approval for orlistat is awaiting a resolution of labeling issues and results of Phase III trials.)
These waist circumference cutpoints lose their incremental predictive power in patients with a BMI ³ 35 kg/m2 because these patients will exceed the cutpoints noted above. These categories denote relative risk, not absolute risk; that is, relative to risk at normal weight. They should not be equated with absolute risk, which is determined by a summation of risk factors. They relate to the need to institute weight loss therapy and do not directly define the required intensity of modification of risk factors associated with obesity.
Risk statusAssessment of a patient's absolute risk status requires examination for the presence of:
Patient motivationWhen assessing the patient's motivation to enter weight loss therapy, the following factors should be evaluated: reasons and motivation for weight reduction; previous history of successful and unsuccessful weight loss attempts; family, friends, and work-site support; the patient's understanding of the causes of obesity and how obesity contributes to several diseases; attitude toward physical activity; capacity to engage in physical activity; time availability for weight loss intervention; and financial considerations. In addition to considering these issues, the health care practitioner needs to heighten a patient's motivation for weight loss and prepare the patient for treatment. This can be done by enumerating the dangers accompanying persistent obesity and by describing the strategy for clinically assisted weight reduction. Reviewing the patients' past attempts at weight loss and explaining how the new treatment plan will be different can encourage patients and provide hope for successful weight loss. Evaluation and TreatmentThe general goals of weight loss and management are: (1) at a minimum, to prevent further weight gain; (2) to reduce body weight; and (3) to maintain a lower body weight over the long term. The overall strategy for the evaluation and treatment of overweight and obese patients is presented in the Treatment Algorithm on the next page. This algorithm applies only to the assessment for overweight and obesity and subsequent decisions based on that assessment. It does not include any initial overall assessment for cardiovascular risk factors or diseases that are indicated.
Goals of weight loss and managementThe initial goal of weight loss therapy is to reduce body weight by approximately 10 percent from baseline. If this goal is achieved, further weight loss can be attempted, if indicated through further evaluation. A reasonable time line for a 10 percent reduction in body weight is 6 months of therapy. For overweight patients with BMIs in the typical range of 27 to 35, a decrease of 300 to 500 kcal/day will result in weight losses of about 1.2 to 1 lb/week and a 10 percent loss in 6 months. For more severely obese patients with BMIs > 35, deficits of up to 500 to 1,000 kcal/day will lead to weight losses of about 1 to 2 lb/week and a 10 percent weight loss in 6 months. Weight loss at the rate of 1 to 2 lb/week (calorie deficit of 500 to 1,000 kcal/day) commonly occurs for up to 6 months. After 6 months, the rate of weight loss usually declines and weight plateaus because of a lesser energy expenditure at the lower weight. Experience reveals that lost weight usually will be regained unless a weight maintenance program consisting of dietary therapy, physical activity, and behavior therapy is continued indefinitely. After 6 months of weight loss treatment, efforts to maintain weight loss should be put in place. If more weight loss is needed, another attempt at weight reduction can be made. This will require further adjustment of the diet and physical activity prescriptions. For patients unable to achieve significant weight reduction, prevention of further weight gain is an important goal; such patients may also need to participate in a weight management program. Strategies for weight loss and weight maintenanceDietary Therapy: A diet that is individually planned and takes into account the patient's overweight status in order to help create a deficit of 500 to 1,000 kcal/day should be an integral part of any weight loss program. A patient may choose a diet of 1,000 to 1,200 kcal/day for women and 1,200 to 1,500 kcal/day for men. Besides decreasing saturated fat, total fats should be 30 percent or less of total calories. Reducing the percentage of dietary fat alone will not produce weight loss unless total calories are also reduced. Isocaloric replacement of fat with carbohydrates will reduce the percentage of calories from fat but will not cause weight loss. Reducing dietary fat, along with reducing dietary carbohydrates, usually will be needed to produce the caloric deficit needed for an acceptable weight loss. When fat intake is reduced, priority should be given to reducing saturated fat to enhance lowering of LDLcholesterol levels. Frequent contacts with the practitioner during dietary therapy help to promote weight loss and weight maintenance at a lower weight.
Physical Activity: An increase in physical activity is an important component of weight loss therapy, although it will not lead to substantially greater weight loss over 6 months. Most weight loss occurs because of decreased caloric intake. Sustained physical activity is most helpful in the prevention of weight regain. In addition, it has a benefit in reducing cardiovascular and diabetes risks beyond that produced by weight reduction alone. For most obese patients, exercise should be initiated slowly, and the intensity should be increased gradually. The exercise can be done all at one time or intermittently over the day. Initial activities may be walking or swimming at a slow pace. The patient can start by walking 30 minutes for 3 days a week and can build to 45 minutes of more intense walking at least 5 days a week. With this regimen, an additional expenditure of 100 to 200 calories per day can be achieved. All adults should set a long-term goal to accumulate at least 30 minutes or more of moderate-intensity physical activity on most, and preferably all, days of the week. This regimen can be adapted to other forms of physical activity, but walking is particularly attractive because of its safety and accessibility. Patients should be encouraged to increase "every day" activities such as taking the stairs instead of the elevator. With time, depending on progress and functional capacity, the patient may engage in more strenuous activities. Competitive sports, such as tennis and volleyball, can provide an enjoyable form of exercise for many, but care must be taken to avoid injury. Reducing sedentary time is another strategy to increase activity by undertaking frequent, less strenuous activities. Behavior Therapy: Strategies, based on learning principles such as reinforcement, that provide tools for overcoming barriers to compliance with dietary therapy and/or increased physical activity are helpful in achieving weight loss and weight maintenance. Specific strategies include self-monitoring of eating habits and physical activity, stress management, stimulus control, problem solving, contingency management, cognitive restructuring, and social support. Combined Therapy: A combined intervention of behavior therapy, an LCD, and increased physical activity provides the most successful therapy for weight loss and weight maintenance. This type of intervention should be maintained for at least 6 months before considering pharmacotherapy. Pharmacotherapy: In carefully selected patients, appropriate drugs can augment LCDs, physical activity, and behavior therapy in weight loss. Weight loss drugs that have been approved by the FDA for long-term use can be useful adjuncts to dietary therapy and physical activity for some patients with a BMI of ³ 30 with no concomitant risk factors or diseases, and for patients with a BMI of ³ 27 with concomitant risk factors or diseases. The risk factors and diseases considered important enough to warrant pharmacotherapy at a BMI of 27 to 29.9 are hypertension, dyslipidemia, CHD, type 2 diabetes, and sleep apnea. Continual assessment by the physician of drug therapy for efficacy and safety is necessary. At the present time, sibutramine is available for long-term use. (Note: FDA approval of orlistat is pending a resolution of labeling issues and results of Phase III trials.) It enhances weight loss modestly and can help facilitate weight loss maintenance. Potential side effects with drugs, nonetheless, must be kept in mind. With sibutramine, increases in blood pressure and heart rate may occur. Sibutramine should not be used in patients with a history of hypertension, CHD, congestive heart failure, arrhythmias, or history of stroke. With orlistat, fat soluble vitamins may require replacement because of partial malabsorption. All patients should be carefully monitored for these side effects. Weight Loss Surgery: Weight loss surgery is one option for weight reduction in a limited number of patients with clinically severe obesity, i.e., BMIs ³ 40 or ³ 35 with comorbid conditions. Weight loss surgery should be reserved for patients in whom efforts at medical therapy have failed and who are suffering from the complications of extreme obesity. Gastrointestinal surgery (gastric restriction [vertical gastric banding] or gastric bypass [Roux-en Y]) is an intervention weight loss option for motivated subjects with acceptable operative risks. An integrated program must be in place to provide guidance on diet, physical activity, and behavioral and social support both prior to and after the surgery. Adapt weight loss programs to meet the needs of diverse patientsStandard treatment approaches for overweight and obesity must be tailored to the needs of various patients or patient groups. Large individual variation exists within any social or cultural group; furthermore, substantial overlap among subcultures occurs within the larger society. There is, therefore, no "cookbook" or standardized set of rules to optimize weight reduction with a given type of patient. However, to be more culturally sensitive and to incorporate patient characteristics in obesity treatment programs: consider and adapt the setting and staffing for the program; consider how the obesity treatment program integrates into other aspects of patient health care and self care; and expect and allow for program modifications based on patient responses and preferences. The issues of weight reduction after age 65 involve such questions as: does weight loss reduce risk factors in older adults; are there risks associated with obesity treatment that are unique to older adults; and does weight reduction prolong the lives of older adults? Although there is less certainty about the importance of treating overweight at older ages than at younger ages, a clinical decision to forgo obesity treatment in older adults should be guided by an evaluation of the potential benefit of weight reduction and the reduction of risk for future cardiovascular events. In the obese patient who smokes, smoking cessation is a major goal of risk factor management. Many well-documented health benefits accompany smoking cessation, but a major obstacle to cessation has been the attendant weight gain observed in about 80 percent of quitters. This weight gain averages 4.5 to 7 lb, but in 13 percent of women and 10 percent of men, weight gain exceeds 28 lb. Weight gain that accompanies smoking cessation has been quite resistant to most dietary, behavioral, or physical activity interventions. The weight gained with smoking cessation is less likely to produce negative health consequences than would continued smoking. For this reason, smoking cessation should be strongly advocated regardless of baseline weight. Prevention of weight gain through diet and physical activity should be stressed. For practical reasons, it may be prudent to avoid initiating smoking cessation and weight loss therapy simultaneously. If weight gain ensues after smoking cessation, it should be managed vigorously according to the guidelines outlined in this report. Although short-term weight gain is a common side effect of smoking cessation, this gain does not rule out the possibility of long-term weight control. |
Summary of Evidence-Based RecommendationsAdvantages of Weight LossThe recommendation to treat overweight and obesity is based not only on evidence that relates obesity to increased mortality but also on randomized controlled trials (RCT) evidence that weight loss reduces risk factors for disease. Thus, weight loss may not only help control diseases worsened by obesity, it may also help decrease the likelihood of developing these diseases. The panel reviewed (RCT) evidence to determine the effect of weight loss on blood pressure and hypertension, serum/plasma lipid concentrations, and fasting blood glucose and fasting insulin. Recommendations focusing on these conditions underscore the advantages of weight loss. Blood pressureTo evaluate the effect of weight loss on blood pressure and hypertension, 76 articles reporting RCTs were considered for inclusion in these guidelines. Of the 45 accepted articles, 35 were lifestyle trials and 10 were pharmacotherapy trials. There is strong and consistent evidence from these lifestyle trials in both overweight hypertensive and nonhypertensive patients that weight loss produced by lifestyle modifications reduces blood pressure levels. Limited evidence exists that decreases in abdominal fat will reduce blood pressure in overweight nonhypertensive individuals, although not independent of weight loss, and there is considerable evidence that increased aerobic activity to increase cardiorespiratory fitness reduces blood pressure (independent of weight loss). There is also suggestive evidence from randomized trials that weight loss produced by most weight loss medications, except for sibutramine, in combination with adjuvant lifestyle modifications will be accompanied by reductions in blood pressure. Based on a review of the evidence from the 45 RCT blood pressure articles, the panel makes the following recommendation:
Weight loss is recommended to lower elevated blood pressure in overweight and obese persons with high blood pressure. Evidence Category A. Serum/plasma lipidsSixty-five RCT articles were evaluated for the effect of weight loss on serum/plasma concentrations of total cholesterol, LDL-cholesterol, very low-density lipoprotein (VLDL)-cholesterol, triglycerides, and HDL-cholesterol. Studies were conducted on individuals over a range of obesity and lipid levels. Of the 22 articles accepted for inclusion in these guidelines, 14 RCT articles examined lifestyle trials while the remaining 8 articles reviewed pharmacotherapy trials. There is strong evidence from the 14 lifestyle trials that weight loss produced by lifestyle modifications in overweight individuals is accompanied by reductions in serum triglycerides and by increases in HDL-cholesterol. Weight loss generally produces some reductions in serum total cholesterol and LDL-cholesterol. Limited evidence exists that a decrease in abdominal fat correlates with improvements in lipids, although the effect may not be independent of weight loss, and there is strong evidence that increased aerobic activity to increase cardiorespiratory fitness favorably affects blood lipids, particularly if accompanied by weight loss. There is suggestive evidence from the eight randomized pharmacotherapy trials that weight loss produced by weight loss medications and adjuvant lifestyle modifications, including caloric restriction and physical activity, does not result in consistent effects on blood lipids. The following recommendation is based on the review ofthe data in these 22 RCT articles:
Weight loss is recommended to lower elevated levels of total cholesterol, LDL-cholesterol, and triglycerides, and to raise low levels of HDL-cholesterol in overweight and obese persons with dyslipidemia. Evidence Category A Blood glucoseTo evaluate the effect of weight loss on fasting blood glucose and fasting insulin levels, 49 RCT articles were reviewed for inclusion in these guidelines. Of the 17 RCT articles accepted, 9 RCT articles examined lifestyle therapy trials and 8 RCT articles considered the effects of pharmacotherapy on weight loss and subsequent changes in blood glucose. There is strong evidence from the nine lifestyle therapy trials that weight loss produced by lifestyle modification reduces blood glucose levels in overweight and obese persons without diabetes, and weight loss reduces blood glucose levels and HbAlc in some patients with type 2 diabetes. There is suggestive evidence that decreases in abdominal fat will improve glucose tolerance in overweight individuals with impaired glucose tolerance, although not independent of weight loss; and there is limited evidence that increased cardio respiratory fitness improves glucose tolerance in overweight individuals with impaired glucose tolerance or diabetes, although not independent of weight loss. In addition, there is suggestive evidence from randomized trials that weight loss induced by weight loss medications does not appear to improve blood glucose levels any better than weight loss through lifestyle therapy in overweight persons both with and without type 2 diabetes. Based on a full review of the data in these 17 RCT articles, the panel makes the following recommendation:
Weight loss is recommended to lower elevated blood glucose levels in overweight and obese persons with type 2 diabetes. Evidence Category A. Measurement of Degree of Overweight and ObesityPatients should have their BMI and levels of abdominal fat measured not only for the initial assessment of the degree of overweight and obesity, but also as a guide to the efficacy of weight loss treatment. Although there are no RCTs that review measurements of overweight and obesity, the panel determined that this aspect of patient care warranted further consideration and that this guidance was deemed valuable. Therefore, the following four recommendations that are included in the Treatment Guidelines were based on nonrandomized studies as well as clinical experience. BMI to assess overweight and obesityThere are a number of accurate methods to assess body fat (e.g., total body water, total body potassium, bioelectrical impedance, and dualenergy X-ray absorptiometry), but no trial data exist to indicate that one measure of fatness is better than any other for following overweight and obese patients during treatment. Since measuring body fat by these techniques is often expensive and is not readily available, a more practical approach for the clinical setting is the measurement of BMI; epidemiological and observational studies have shown that BMI provides an acceptable approximation of total body fat for the majority of patients. Because there are no published studies that compare the effectiveness of different measures for evaluating changes in body fat during weight reduction, the panel bases its recommendations on expert judgement from clinical experience:
Practitioners should use the BMI to assess overweight and obesity. Body weight alone can be used to follow weight loss, and to determine efficacy of therapy. Evidence Category C. BMI to estimate relative riskIn epidemiological studies, BMI is the favored measure of excess weight to estimate relative risk of disease. BMI correlates both with morbidity and mortality; the relative risk for CVD risk factors and CVD incidence increases in a graded fashion with increasing BMI in all population groups. Moreover, calculating BMI is simple, rapid, and inexpensive, and can be applied generally to adults. The panel, therefore, makes this recommendation:
The BMI should be used to classify overweight and obesity and to estimate relative risk of disease compared to normal weight. Evidence Category C. Assessing abdominal fatFor the most effective technique for assessing abdominal fat content, the panel considered measures of waist circumference, waist-to-hip ratio (WHR), magnetic resonance imaging (MRI), and computed tomography. Evidence from epidemiological studies shows waist circumference to be a better marker of abdominal fat content than WHR, and that it is the most practical anthropometric measurement for assessing a patient's abdominal fat content before and during weight loss treatment. Computed tomography and MRI are both more accurate but impractical for routine clinical use. Based on evidence that waist circumference is a better marker than WHR and taking into account that the MRI and computed tomography techniques are expensive and not readily available for clinical practice the panel makes the following recommendation:
The waist circumference should be used to assess abdominal fat content. Evidence Category C. Sex-specific measurementsEvidence from epidemiological studies indicates that a high waist circumference is associated with an increased risk for type 2 diabetes, dyslipidemia, hypertension, and CVD. Therefore, the panel judged that sex-specific cutoffs for waist circumference can be used to identify increased risk associated with abdominal fat in adults with a BMI in the range of 25 to 34.9. These cutpoints can be applied to all adult ethnic or racial groups. On the other hand, if a patient is very short, or has a BMI above the 25 to 34.9 range, waist cutpoints used for the general population may not be applicable. Based on the evidence from nonrandomized studies, the panel makes this recommendation:
For adult patients with a BMI of 25 to 34.9 kg/m2, sex-specific waist circumference cutoffs should be used in conjunction with BMI to identify increased disease risks. Evidence Category C. Goals For Weight LossThe general goals of weight loss and management are to reduce body weight, to maintain a lower body weight over the long term, and to prevent further weight gain. Evidence indicates that a moderate weight loss can be maintained over time if some form of therapy continues. It is better to maintain a moderate weight loss over a prolonged period than to regain from a marked weight loss. Initial goal of weight loss from baselineThere is strong and consistent evidence from randomized trials that overweight and obese patients in well-designed programs can achieve a weight loss of as much as 10 percent of baseline weight. In the diet trials, an average of 8 percent of baseline weight was lost. Since this average includes persons who did not lose weight, an individualized goal of 10 percent is reasonable. The panel, therefore, recommends that:
The initial goal of weight loss therapy should be to reduce body weight by approximately 10 percent from baseline. With success, further weight loss can be attempted if indicated through furth er assessment. Evidence Category A. Amount of weight lossRandomized trials suggest that weight loss at the rate of 1 to 2 lb/week (calorie deficit of 500 to 1,000 kcal/day) commonly occurs for up to 6 months.
Weight loss should be about 1 to 2 lb/week for a period of 6 months, with the subsequent strategy based on the amount of weight lost. Evidence Category B.
How to Achieve Weight LossThe panel reviewed relevant treatment strategies designed for weight loss that can also be used to foster long-term weight control and prevention of weight gain. The consequent recommendations emphasize the potential effectiveness of weight control using multiple interventions and strategies, including dietary therapy, physical activity, behavior therapy, pharmacotherapy, and surgery, as well as combinations of these strategies. Dietary therapyThe panel reviewed 86 RCT articles to determine the effectiveness of diets on weight loss (including LCDs, very low-calorie diets (VLCDs), vegetarian diets, American Heart Association dietary guidelines, the NCEP's Step I diet with caloric restriction, and other low-fat regimens with varying combinations of macronutrients). Of the 86 articles reviewed, 48 were accepted for inclusion in these guidelines. These RCTs indicate strong and consistent evidence that an average weight loss of 8 percent of initial body weight can be obtained over 3 to 12 months with an LCD and that this weight loss effects a decrease in abdominal fat; and, although lower-fat diets without targeted caloric reduction help promote weight loss by producing a reduced caloric intake, lower-fat diets with targeted caloric reduction promote greater weight loss than lower-fat diets alone. Further, VLCDs produce greater initial weight losses than LCDs (over the long term of >1 year, weight loss is not different than that of the LCDs). In addition, randomized trials suggest that no improvement in cardiorespiratory fitness as measured by VO2 max appears to occur in obese adults who lose weight on LCDs alone without physical activity. The following recommendations are based on the evidence extracted from the 48 accepted articles:
LCDs are recommended for weight loss in overweight and obese persons. Evidence Category A. Reducing fat as part of an LCD is a practical way to reduce calories. Evidence Category A. Physical activityEffects of Physical Activity on Weight Loss .Twenty-three RCT articles were reviewed to determine the effect of physical activity on weight loss, abdominal fat (measured by waist circumference), and changes in cardiorespiratory fitness (VO2max). Thirteen of these articles were accepted for inclusion in these guidelines. A review of these articles reveals strong evidence that physical activity alone, i.e., aerobic exercise, in obese adults results in modest weight loss and that physical activity in overweight and obese adults increases cardiorespiratory fitness, independent of weight loss. Randomized trials suggest that increased physical activity in overweight and obese adults reduces abdominal fat only modestly or not at all, and that regular physical activity independently reduces the risk for CVD. The panel's recommendation on physical activity is based on the evidence from these 13 articles:
Physical activity is recommended as part of a comprehensive weight loss therapy and weight control program because it: (1) modestly contributes to weight loss in overweight and obese adults (Evidence Category A), (2) may decrease abdominal fat (Evidence Category B), (3) increases cardio respiratory fitness (Evidence Category A), and (4) may help with maintenance of weight loss (Evidence Category C). Effects of Physical Activity and Diet on Weight Loss (Combined Therapy). Twenty-three RCT articles were reviewed to determine the effects on body weight of a combination of a reduced-calorie diet with increased physical activity. Fifteen of these articles were accepted for inclusion in the guidelines. These articles contain strong evidence that the combination of a reduced-calorie diet and increased physical activity produces greater weight loss than diet alone or physical activity alone, and that the combination of diet and physical activity improves cardiorespiratory fitness as measured by VO2max in overweight and obese adults when compared to diet alone. The combined effect of a reduced calorie diet and increased physical activity seemingly produced modestly greater reductions in abdominal fat than either diet alone or physical activity alone, although it has not been shown to be independent of weight loss. The panel's following recommendations are based on the evidence from these articles:
The combination of a reduced calorie diet and increased physical activity is recommended since it produces weight loss that may also result in decreases in abdominal fat and increases in cardiorespiratory fitness. Evidence Category A. Behavior therapyThirty-six RCTs were reviewed to evaluate whether behavior therapy provides additional benefit beyond other weight loss approaches, as well as to compare various behavioral techniques. Of the 36 RCTs reviewed, 22 were accepted. These RCTs strongly indicate that behavioral strategies to reinforce changes in diet and physical activity in obese adults produce weight loss in the range of 10 percent over 4 months to 1 year. In addition, no one behavior therapy appeared superior to any other in its effect on weight loss; multimodal strategies appear to work best and those interventions with the greatest intensity appear to be associated with the greatest weight loss. Long-term follow-up of patients undergoing behavior therapy shows a return to baseline weight for the great majority of subjects in the absence of continued behavioral intervention. Randomized trials suggest that behavior therapy, when used in combination with other weight loss approaches, provides additional benefits in assisting patients to lose weight short-term, i.e., 1 year (no additional benefits are found at 3 to 5 years). The panel found little evidence on the effect of behavior therapy on cardiorespiratory fitness. Evidence from these articles provided the basis for the following recommendation:
Behavior therapy is a useful adjunct when incorporated into treatment for weight loss and weight maintenance. Evidence Category B. There is also suggestive evidence that patient motivation is a key component for success in a weight loss program. The panel, therefore, makes the following recommendation:
Practitioners need to assess the patient's motivation to enter weight loss therapy; assess the readiness of the patient to implement the plan and then take appropriate steps to motivate the patient for treatment. Evidence Category D. Summary of lifestyle therapyThere is strong evidence that combined interventions of an LCD, increased physical activity, and behavior therapy provide the most successful therapy for weight loss and weight maintenance. The panel makes the following recommendation:
Weight loss and weight maintenance therapy should employ the combination of LCDs, increased physical activity, and behavior therapy. Evidence Category A. PharmacotherapyA review of 44 pharmacotherapy RCT articles provides strong evidence that pharmacological therapy (which has generally been studied along with lifestyle modification, including diet and physical activity) using dexfenfluramine, sibutramine, orlistat, or phentermine/fenfluramine results in weight loss in obese adults when used for 6 months to 1 year. Strong evidence also indicates that appropriate weight loss drugs can augment diet, physical activity, and behavior therapy in weight loss. Adverse side effects from the use of weight loss drugs have been observed in patients. As a result of the observed association of valvular heart disease in patients taking fenfluramine and dexfenfluramine alone or in combination, these drugs have been withdrawn from the market. Weight loss drugs approved by the FDA for long-term use may be useful as an adjunct to diet and physical activity for patients with a BMI of ³ 30 with no concomitant obesity- related risk factors or diseases, as well as for patients with a BMI of ³ 27 with concomitant risk factors or diseases; moreover, using weight loss drugs singly (not in combination) and starting with the lowest effective doses can decrease the likelihood of adverse effects. Based on this evidence, the panel makes the following recommendation:
Weight loss drugs approved by the FDA may be used as part of a comprehensive weight loss program, including dietary therapy and physical activity for patients with a BMI of ³ 30 with no concomitant obesity-related risk factors or diseases, and for patients with a BMI of ³ 27 with concomitant obesity-related risk factors or diseases. Weight loss drugs should never be used without concomitant lifestyle modifications. Continual assessment of drug therapy for efficacy and safety is necessary. If the drug is efficacious in helping the patient to lose and/or maintain weight loss and there are no serious adverse effects, it can be continued. If not, it should be discontinued. Evidence Category B. Weight loss surgeryThe panel reviewed 14 RCTs that examined the effect of surgical procedures on weight loss; 8 were deemed appropriate. All of the studies included individuals who had a BMI of 40 kg/m2 or above, or a BMI of 35 to 40 kg/m2 with comorbidity. These trials provide strong evidence that surgical interventions in adults with clinically severe obesity, i.e., BMIs ³ 40 or ³ 35 with comorbid conditions, result in substantial weight loss, and suggestive evidence that lifelong medical surveillance after surgery is necessary. Therefore, the panel makes the following recommendation:
Weight loss surgery is an option for carefully selected patients with clinically severe obesity (BMI ³ 40 or ³ 35 with comorbid conditions) when less invasive methods of weight loss have failed and the patient is at high risk for obesity-associated morbidity or mortality Evidence Category B. Goals For Weight Loss MaintenanceOnce the goals of weight loss have been successfully achieved, maintenance of a lower body weight becomes the challenge. Whereas studies have shown that weight loss is achievable, it is difficult to maintain over a long period of time (3 to 5 years). In fact, the majority of persons who lose weight, once dismissed from clinical therapy, frequently regain itso the challenge to the patient and the practitioner is to maintain the weight loss. Successful weight reduction thus depends on continuing a maintenance program on a long-term basis. In the past, obtaining the goal of weight loss has been considered the end of weight loss therapy. Observation, monitoring, and encouragement of patients who have successfully lost weight should be continued long term. The panel's recommendations on weight loss maintenance are derived from RCT evidence as well as nonrandomized and observational studies. Weight maintenance phaseRCTs from the Behavior Therapy section above suggest that lost weight usually will be regained unless a weight maintenance program consisting of dietary therapy, physical activity, and behavior therapy is continued indefinitely. Drug therapy in addition may be helpful during the weight maintenance phase. The panel also reviewed RCT evidence that considered the rate of weight loss and the role of weight maintenance. These RCTs suggest that after 6 months of weight loss treatment, efforts to maintain weight loss are important. Therefore, the panel recommends the following:
After successful weight loss, the likelihood of weight loss maintenance is enhanced by a program consisting of dietary therapy, physical activity, and behavior therapy which should be continued indefinitely. Drug therapy can also be used. However, drug safety and efficacy beyond 1 year of total treatment have not been established. Evidence Category B. Strong evidence indicates that better weight loss results are achieved with dietary therapy when the duration of the intervention is at least 6 months. Suggestive evidence also indicates that during dietary therapy, frequent contacts between professional counselors and patients promote weight loss and maintenance. Therefore, the panel recommends the following:
The literature suggests that weight loss and weight maintenance therapies that provide a greater frequency of contacts between the patient and the practitioner and are provided over the long term should be utilized whenever possible. This can lead to more successful weight loss and weight maintenance. Evidence Category C Special Treatment GroupsThe needs of special patient groups must be addressed when considering treatment options for overweight and obesity. The guidelines focus on three such groups including smokers, older adults, and diverse patient populations. SmokersCigarette smoking is a major risk factor for cardiopulmonary disease. Because of its attendant high risk, smoking cessation is a major goal of risk-factor management. This aim is especially important in the overweight or obese patient, who usually carries excess risk from obesity-associated risk factors. Thus, smoking cessation in these patients becomes a high priority for risk reduction. Smoking and obesity together apparently compound cardiovascular risk, but fear of weight gain upon smoking cessation is an obstacle for many patients. Therefore, the panel recommends that:
All smokers, regardless of their weight status, should quit smoking. Evidence Category A. Prevention of weight gain should be encouraged and if weight gain does occur, it should be treated through dietary therapy, physical activity, and behavior therapy, maintaining the primary emphasis on the importance of abstinence from smoking. Evidence Category C.H6>Older adults The general nutritional safety of weight reduction at older ages is of concern because restrictions on overall food intake due to dieting could result in inadequate intake of protein or essential vitamins or minerals. In addition, involuntary weight loss indicative of occult disease might be mistaken for success in voluntary weight reduction. These concerns can be alleviated by providing proper nutritional counseling and regular body weight monitoring in older persons for whom weight reduction is prescribed. A review of several studies indicates that age alone should not preclude treatment for obesity in adult men and women. In fact, there is evidence from RCTs that weight reduction has similar effects in improving cardiovascular disease risk factors in older and younger adults. Therefore, in the panel's judgment:
A clinical decision to forego obesity treatment in older adults should be guided by an evaluation of the potential benefits of weight reduction for day-to-day functioning and reduction of the risk of future cardiovascular events, as well as the patient's motivation for weight reduction. Care must be taken to ensure that any weight reduction program minimizes the likelihood of adverse effects on bone health or other aspects of nutritional status. Evidence Category D. Diverse patient populationsStandard obesity treatment approaches should be tailored to the needs of various patients or patient groups. It is, however, difficult to determine from the literature how often this occurs, how specific programs and outcomes are influenced by tailoring, and whether it makes weight loss programs more effective. After reviewing two RCTs, four cross-sectional studies, and four intervention studies, as well as additional published literature on treatment approaches with diverse patient populations, the panel recommends the following:
The possibility that a standard approach to weight loss will work differently in diverse patient populations must be considered when setting expectations about treatment outcomes. Evidence Category B.
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Evaluation and Treatment StrategyWhen physicians encounter patients in the clinical setting, the opportunity exists for identifying overweight and obesity and accompanying risk factors and for initiating treatment for both the weight and the risk factors, as well as chronic diseases such as CVD and type 2 diabetes. When assessing a patient for treatment of overweight and obesity, consider the patient's weight, waist circumference, and the presence of risk factors. The strategy for the evaluation and treatment of overweight patients is presented in Figure 1 (Treatment Algorithm). This algorithm applies only to the assessment for overweight and obesity and subsequent decisions based on that assessment. It does not reflect any initial overall testing for other conditions and diseases that the physician may wish to do. In overweight patients, control of cardiovascular risk factors deserves equal emphasis as weight loss therapy. Reductions of risk factors will reduce the risk for cardiovascular disease whether or not efforts at weight loss are successful. The panel recognizes that the assessment for overweight and obesity may take place as part of an overall health assessment; however, for clarity, the algorithm focuses only on the evaluation and treatment of overweight and obesity.
Each step (designated by a box) in this process is reviewed in this section. Box 1: "Patient Encounter" A patient encounter is defined as any interaction between a health care practitioner (generally a physician, nurse practitioner or physician's assistant) that provides the opportunity to assess a patient's weight status and provide advice, counseling, or treatment. Box 2: "History of Overweight or Recorded BMI ³ 25" The practitioner must seek to determine whether the patient has ever been overweight. While a technical definition is provided, a simple question such as "Have you ever been overweight?" will accomplish the same goal. Questions directed towards weight history, dietary habits, physical activities, and medications may provide useful information about the origins of obesity in particular patients. Box 3: "BMI Measured in Past 2 Years" For those who have not been overweight, a 2-year interval is appropriate for the reassessment of BMI. While this time span is not evidence based, it is believed to be a reasonable compromise between the need to identify weight gain at an early stage and the need to limit the time, effort, and cost of repeated measurements. Box 4: "Measure Weight, Height, Waist Circumference; Calculate BMI" Weight must be measured so that the BMI can be calculated. Most charts are based on weights obtained with the patient wearing undergarments and no shoes. BMI can be manually calculated (kg/[height in meters)2, but is more easily obtained from a nomogram. Waist circumference is important because evidence suggests that abdominal fat is a particularly strong determinant of cardiovascular risk in those with a BMI of 25 to 34.9 kg/m. Increased waist circumference can also be a marker of increased risk even in persons of normal weight. A nutrition assessment will also help to assess the diet and physical activity habits of overweight patients. Box 5: "BMI ³ 25, OR Waist Circumference > 88 cm(F) or > 102 cm(M)" These cutpoints divide overweight from normal weight and are consistent with other national and international guidelines. The relation between weight and mortality is J-shaped, and evidence suggests that the right side of the "J" begins to rise at a BMI of 25. Waist circumference is incorporated as an "or" factor because some patients with BMI lower than 25 will have disproportionate abdominal fat, and this increases their cardiovascular risk despite their low BMI. These abdominal circumference values are not necessary for patients with a BMI ³ 35 kg/m. Box 6: "Assess Risk Factors" Risk assessment for CVD and diabetes in a person with evident obesity will include special considerations for the history, physical examination, and laboratory examination. Of greatest urgency is the need to detect existing CVD or end-organ damage. Since the major risk of obesity is indirect (obesity elicits or aggravates hypertension, dyslipidemias, and diabetes, which cause cardiovascular complications), the management of obesity should be implemented in the context of these other risk factors. While there is no direct evidence demonstrating that addressing risk factors increases weight loss, treating the risk factors through weight loss is a recommended strategy. Box 7: "BMI ³ 30, OR ([BMI 25 to 29.9 OR Waist Circumference > 88 cm(F) or > 102 cm(M)] AND ³ 2 risk factors)" The panel recommends that all patients meeting these criteria attempt to lose weight. However, it is important to ask the patient whether or not they want to lose weight. Those with BMIs between 25 and 29.9 kg/m2 who have one or no risk factors should work on maintaining their current weight rather than embark on a weight reduction program. The panel recognizes that the decision to lose weight must be made in the context of other risk factors (e.g., quitting smoking is more important than losing weight) and patient preferences. Box 8: "Clinician and Patient Devise Goals" The decision to lose weight must be made jointly between the clinician and patient. Patient involvement and investment is crucial to success. The patient may choose not to lose weight but rather to prevent further weight gain as a goal. The panel recommends as an initial goal the loss of 10 percent of baseline weight, to be lost at a rate of 1 to 2 lb/week, establishing an energy deficit of 500 to 1,000 kcal/day. For individuals who are overweight, a deficit of 300 to 500 kcal/day may be more appropriate, providing a weight loss of about 1/2 lb/week. Also, there is evidence that an average of 8 percent of weight can be lost in a 6-month period. Since the observed average 8 percent weight loss includes people who do not lose weight, an individual goal of 10 percent is reasonable. After 6 months, most patients will equilibrate (caloric intake balancing energy expenditure) and will require adjustment of energy balance if they are to lose more weight. The three major components of weight loss therapy are dietary therapy, increased physical activity, and behavior therapy. Lifestyle therapy should be tried for at least six months before considering pharmacotherapy. In addition, pharmacotherapy should be considered as an adjunct to lifestyle therapy in patients with a BMI ³ 30 with no concomitant obesity-related risk factors or diseases, or for patients with a BMI ³ 27 with concomitant obesity-related risk factors or diseases. The risk factors or diseases considered important enough to warrant pharmacotherapy at a BMI of 27 to 29.9 are hypertension, dyslipidemia, CHD, type 2 diabetes, and sleep apnea. However, sibutramine, the only FDA approved drug for long-term use, should not be used in patients with a history of hypertension, CHD, congestive heart failure, arrhythmias, or history of stroke. Certain patients may be candidates for weight loss surgery. Each component of weight loss therapy can be introduced briefly. The selection of weight loss methods should be made in the context of patient preferences, analysis of past failed attempts, and consideration of the available resources. Box 9: "Progress Being Made/Goal Achieved" During the acute weight loss period and at 6- month and 1-year follow-up visits, the patients should be weighed, BMI calculated, and progress assessed. If at any time it appears that the program is failing, a reassessment should take place to determine the reasons (see Box 10). If pharmacotherapy is being used, appropriate monitoring for side effects is recommended. If a patient can achieve the recommended 10 percent reduction in body weight in 6 months to 1 year, this change in weight can be considered good progress. The patient can then enter the phase of weight maintenance and long-term monitoring. It is important for the practitioner to recognize that some persons are more apt to lose or gain weight on a given regimen and that this phenomenon cannot always be attributed to degree of compliance. However, if significant obesity remains and absolute risk from obesity-associated risk factors remains high, at some point an effort should be made to reinstitute weight loss therapy to achieve further weight reduction. Once a limit of weight loss has been obtained, the practitioner is responsible for long-term monitoring of risk factors and for encouraging the patient to maintain a reduced weight level. Box 10: "Assess Reasons for Failure to Lose Weight" If a patient fails to achieve the recommended 10 percent reduction in body weight in 6 months or 1 year, a reevaluation is required. A critical question is whether the level of motivation is high enough to continue clinical therapy. If motivation is high, revise the goals and strategies (see Box 8). If motivation is not high, clinical therapy should be discontinued, but the patient should be encouraged to embark on efforts to lose weight or to at least avoid further weight gain. Even if weight loss therapy is stopped, risk factor management must be continued. Failure to achieve weight loss should prompt the practitioner to investigate energy intake (dietary recall including alcohol intake, daily intake logs), energy expenditure (physical activity diary), attendance at behavior therapy group meetings, recent negative life events, family and societal pressures, or evidence of detrimental psychiatric problems (depression, binge eating disorder). If attempts to lose weight have failed, and the BMI is ³ 40, surgical therapy should be considered. Box 11: "Maintenance Counseling" Evidence suggests that over 80 percent of persons who lose weight will gradually regain it. Patients who continue on weight maintenance programs have a greater chance of keeping weight off. Maintenance consists of continued contact with the health care practitioner for continued education, support, and medical monitoring. Box 12: "Does the Patient Want to Lose Weight?" All patients who are overweight (BMI 25 to 29.9), or do not have a high waist circumference, and have few (0 to 1) cardiovascular risk factors and do not w ant to lose weight, should be counseled regarding the need to keep their weight at or below its present level. Patients who wish to lose weight should be guided per Boxes 8 and 9. The justification for offering these overweight patients the option of maintaining (rather than losing) weight is that their health risk, while higher than that of persons with a BMI < 25, is only moderately increased. Box 13: "Advise to Maintain Weight/Address Other Risk Factors" Those who have a history of overweight and are now at appropriate weight, and those who are overweight and not obese but wish to focus on maintenance of their current weight, should be provided with counseling and advice so that their weight does not increase. An increase in weight increases their health risk and should be prevented. The physician should actively promote prevention strategies including enhanced attention by the patient to diet, physical activity, and behavior therapy. For addressing other risk factors, see Box 6, because even if weight loss cannot be addressed, other risk factors should be covered. Box 14: "History of BMI ³ 25" This box differentiates those who are not overweight now and never have been from those with a history of overweight; see Box 2. Box 15: "Brief Reinforcement" Those who are not overweight and never have been should be advised of the importance of staying in this category. Box 16: "Periodic Weight, BMI, and Waist Circumference Check" Patients should receive periodic monitoring of their weight, BMI, and waist circumference. Patients who are not overweight or have no history of overweight should be screened for weight gain every 2 years. This time span is a reasonable compromise between the need to identify weight gain at an early stage and the need to limit the time, effort, and the cost of repeated measurements.
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Exclusion From Weight Loss TherapyPatients in whom weight loss therapy is not appropriate include most pregnant or lactating women, those with serious psychiatric illness, and patients who have a variety of serious illnesses in whom caloric restriction might exacerbate the illness. |
Patient MotivationAssessment of patient motivation is a prerequisite for weight loss therapy. Weight reduction in the clinical setting represents a major investment of time and effort on the part of the health care team and expense to the patient. For these reasons, motivation for weight loss should be relatively high before initiating clinical therapy. At the same time, it is the duty of the primary care practitioner to heighten a patient's motivation for weight loss when such is perceived to be of significant benefit for risk reduction. This can be done by enumerating the dangers associated with persistent obesity and by describing the strategy for clinically assisted weight reduction. For patients who are not motivated (or able) to enter clinical weight loss therapy, appropriate management of risk factors (e.g., high serum cholesterol, hypertension, smoking, and type 2 diabetes) is still necessary. Sustained weight reduction may facilitate control of cardiovascular risk factors and delay the onset of type 2 diabetes.
Rationale: Assessment of the patient's motivation for treatment by the practitioner is important in the decision to initiate a weight loss program. The following factors must be evaluated:
One of the most important aspects of the initial evaluation is to prepare patients for treatment. Reviewing patients' past attempts at weight loss and explaining how the new treatment plan will be different can encourage patients and provide hope for successful weight loss. It is helpful to discuss the proposed course of treatment and describe necessary behaviors, such as keeping diaries of food intake and physical activity. Finally, given the social stigmatization that obese patients often feel, even from health care professionals, the initial evaluation is an opportunity to show the patient respect, concern, and hope. A patient who has shared feelings about being overweight and previous attempts to lose weight with a sympathetic listener may be more willing to consider new ideas and information. A partnership in which the patient feels supported and understood can help to sustain the necessary motivation for the difficult task of weight loss and maintenance.
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Goals of Weight Loss and ManagementThe general goals of weight loss and management are: (1) to reduce body weight; and (2) to maintain a lower body weight over the long term; or (3) at a minimum, to prevent further weight gain. Specific targets for each of these goals can be considered. Weight LossTarget levels for weight lossThe initial target goal of weight loss therapy for overweight patients is to decrease body weight by about 10 percent. If this target can be achieved, consideration can be given to the next step of further weight loss.
Evidence Statement: Overweight and obese patients in well-designed programs can achieve a weight loss of as much as 10 percent of baseline weight, a weight loss that can be maintained for a sustained period of time (1 year or longer). Evidence Category A. Rationale: The rationale for this initial goal is that even moderate weight loss, i.e., 10 percent of initial body weight, can significantly decrease the severity of obesity-associated risk factors. It can also set the stage for further weight loss, if indicated. Available evidence indicates that an average weight loss of 8 percent can be achieved in 6 months; however, since the observed average 8 percent includes people who do not lose weight, an individual goal of 10 percent is reasonable. This degree of weight loss can be achieved and is realistic, and moderate weight loss can be maintained over time. It is better to maintain a moderate weight loss over a prolonged period than to regain from a marked weight loss. The latter is counterproductive in terms of time, costs, and self-esteem. Patients generally will wish to lose more weight than 10 percent, and will need to be counseled and persuaded of the appropriateness of this initial goal. 553, 554 Further weight loss can be considered after this initial goal is achieved and maintained for 6 months.
Recommendation: The initial goal of weight loss therapy should be to reduce body weight by approximately 10 percent from baseline. With success, further weight loss can be attempted, if indicated through further assessment. Evidence Category A. Rate of weight lossA reasonable time line for weight loss is to achieve a 10 percent reduction in body weight over 6 months of therapy. For overweight patients with BMIs in the typical range of 27 to 35, a decrease of 300 to 500 kcal/day will result in weight losses of about 1.2 to 1 lb/week and a 10 percent weight loss in 6 months. For more severely obese patients with BMIs ³ 35, deficits of up to 500 to 1,000 kcal/day will lead to weight losses of about 1 to 2 lb/week and a 10 percent weight loss in 6 months.
Evidence Statement: Weight loss at the rate of 1 to 2 lb/week (calorie deficit of 500 to 1,000 kcal/day) commonly occurs for up to 6 months, at which point weight loss begins to plateau unless a more restrictive regimen is implemented. Evidence Category B. Rationale: To achieve significant weight loss, an energy deficit must be created and maintained. Weight can be lost at a rate of 1 to 2 lb/week with a calorie deficit of 500 to 1,000 kcal/day. After 6 months, this caloric deficit theoretically should result in a loss of 26 to 52 lb. However, the average amount of weight lost actually observed over this time period usually is in the range of 20 to 25 lb. A greater rate of weight loss does not yield a better result at the end of 1 year. 437 It is difficult for most patients to continue to lose weight after a period of 6 months due to changes in resting metabolic rates and difficulty in adhering to treatment strategies, although some can do so. To continue to lose weight, diet and physical activity goals need to be revised to create an energy deficit at the lower weight, since energy requirements decrease as weight is decreased. To achieve additional weight loss, the patient must further decrease calories and/or increase physical activity. Many studies show that rapid weight reduction almost always is followed by regaining of weight. Moreover, with rapid weight reduction, there is an increased risk for gallstones and, possibly, electrolyte abnormalities.
Recommendation: Weight loss should be about 1 to 2 lb/week for a period of 6 months with the subsequent strategy based on the amount of weight lost. Evidence Category B. Weight maintenance at lower weightOnce the goals of weight loss have been successfully achieved, maintenance of a lower body weight becomes a major challenge. In the past, obtaining the goal of weight loss has been considered the end of weight loss therapy. Unfortunately, once patients are dismissed from clinical therapy, they frequently regain the lost weight. This report recommends that observation, monitoring, and encouragement of patients who have successfully lost weight be continued on a long-term basis.
Evidence Statement: After 6 months of weight loss treatment, efforts to maintain weight loss through diet, physical activity, and behavior therapy are important. Evidence Category B. Rationale: After 6 months of weight loss, the rate of weight loss usually declines and plateaus. The primary care practitioner and patient should recognize that at this point, weight maintenance, the second phase of the weight loss effort, should take priority. Successful weight maintenance is defined as a weight regain of < 3 kg (6.6 lb) in 2 years and a sustained reduction in waist circumference of at least 4 cm. If a patient wishes to lose more weight after a period of weight maintenance, the procedure for weight loss outlined above can be repeated.
Recommendation: A weight maintenance program should be a priority after the initial 6 months of weight loss therapy. Evidence Category B. Rationale: After a patient has achieved the goals of weight loss, the combined modalities of therapy (dietary therapy, physical activity, and behavior therapy) must be continued indefinitely; otherwise, excess weight likely will be regained. Numerous strategies are available for motivating the patient; all of these require that the practitioner continue to communicate frequently with the patient. Long-term monitoring and encouragement can be accomplished in several ways: by regular clinic visits, at group meetings, or via telephone or E-mail. The longer the weight maintenance phase can be sustained, the better the prospects for long-term success in weight reduction. Drug therapy may also be helpful during the weight maintenance phase.
Recommendation: After successful weight loss, the likelihood of weight loss maintenance is enhanced by a program consisting of dietary therapy, physical activity, and behavior therapy, which should be continued indefinitely. Drug therapy can also be used. However, drug safety and efficacy beyond 1 year of total treatment have not been established. Evidence Category B. Prevention of further weight gainSome patients may not be able to achieve significant weight reduction. In such patients, an important goal is to prevent further weight gain that would exacerbate disease risk. Thus, prevention of further weight gain may justify entering a patient into weight loss therapy. Prevention of further weight gain can be considered a partial therapeutic success for many patients. Moreover, if further weight gain can be prevented, this achievement may be an important first step toward beginning the weight loss process. Primary care practitioners ought to recognize the importance of this goal for those patients who are not able to immediately lose weight. The need to prevent weight gain may warrant maintaining patients in a weight management program for an extended period. |
Strategies For Weight Loss and Weight MaintenanceDietary TherapyIn the majority of overweight and obese patients, adjustment of the diet to reduce caloric intake will be required. Dietary therapy consists, in large part, of instructing patients on how to modify their diets to achieve a decrease in caloric intake. A key element of the current recommendation is the use of a moderate reduction in caloric intake to achieve a slow but progressive weight loss. Ideally, caloric intake should be reduced only to the level required to maintain weight at the desired level. If this level of caloric intake is achieved, excess weight will gradually disappear. In practice, somewhat greater caloric deficits are used in the period of active weight loss, but diets with very low calories are to be avoided. Finally the composition of the diet should be modified to minimize other cardiovascular risk factors. The centerpiece of dietary therapy for weight loss in overweight patients is a low-calorie diet (LCD) (800 to 1,500 kcal/day). This diet is to be distinguished from a very low-calorie diet (VLCD) (250 to 800 kcal/day), which has been unsuccessful in achieving weight loss over the long term. The LCD recommended in this report also contains nutrient compositions that will decrease other risk factors, notably, high serum cholesterol and hypertension. Evidence Statement: LCDs can reduce total body weight by an average of 8 percent and help reduce abdominal fat content over a period of approximately 6 months. Evidence Category A. Rationale: A decrease in calorie intake is the most important dietary component of weight loss and maintenance. LCDs have been shown to reduce total body weight by an average of 8 percent over a period of 6 months, accompanied by significant reductions in waist circumference. Since this represents an average that includes individuals who did not lose weight, an individual average goal of 10 percent is feasible. When weight loss occurs, the loss consists of about 75 percent fat and 25 percent lean tissue. A deficit of 500 to 1,000 kcal/day will produce a weight loss of 70 to 140 grams/day, or 490 to 980 grams/week (1 to 2 lb/week). A deficit of 300 to 500 kcal/day will produce a weight loss of 40 to 70 grams/day, or 280 to 490 grams/week (1/2 to 1 lb/week) A patient may choose a diet of 1,000 to 1,200 kcal for women and 1,200 to 1,500 kcal for men. VLCDs (less than 800 kcal/day) are not recommended for weight loss therapy because the deficits are too great, and nutritional inadequacies will occur unless VLCDs are supplemented with vitamins and minerals. Moreover, clinical trials show that LCDs are just as effective as VLCDs in producing weight loss after 1 year. Although more weight is initially lost with VLCDs, more is usually regained. Further, rapid weight reduction does not allow for gradual acquisition of changes in eating behavior. Successful behavior therapy is the key to longterm maintenance of weight at a reduced level. Finally, patients using VLCDs are at increased risk for developing gallstones. Successful weight reduction by LCDs is more likely to occur when consideration is given to a patient's food preferences in tailoring a particular diet. Care should be taken to be sure that all of the recommended dietary allowances are met; this may require use of a dietary supplement. Dietary education is a necessary ingredient in achieving adjustment to an LCD. Educational efforts should pay particular attention to the following topics:
The Step I Diet in ATP II provides an appropriate nutrient composition for an LCD diet. The composition of the diet is presented in Table 4. Recommendation: A diet that is individually planned to help create a deficit of 500 to 1,000 kcal/day should be an integral part of any program aimed at achieving a weight loss of 1 to 2 lb/week. Evidence Category A. Recommendation: Reducing dietary fat alone without reducing calories is not sufficient for weight loss. However, reducing dietary fat, along with reducing dietary carbohydrates, can facilitate caloric reduction. Evidence Category A. Evidence Statement: Optimally, dietary therapy should last at least 6 months. Evidence Category A. Rationale: Many studies suggest that the rate of weight loss diminishes after about 6 months. Shorter periods of dietary therapy usually result in lesser weight reductions. Therapeutic efforts should be directed toward behavior therapy as well as maintaining LCDs. Evidence Statement: During dietary therapy, frequent contacts between professional counselors and patients promote weight loss and maintenance. Evidence Category C. Rationale: Frequent clinical encounters during the initial 6 months of weight reduction appear to facilitate reaching the goals of therapy. During the period of active weight loss, regular visits of at least once per month and preferably more often with a health professional for the purposes of reinforcement, encouragement, and monitoring will facilitate weight reduction. Weekly group meetings can be conducted at a low cost, and can contribute to favorable behavior changes. However, no clinical trials have been specifically designed to test the relative efficacy of different frequencies of encounters with physicians, dietitians, or others in the weight loss team. Evidence Statement: The amount of time spent with the patient favorably affects weight change in overweight or obese adults given dietary therapy. Evidence Category D. Rationale: Training of a health professional in techniques of weight reduction, especially in behavior therapy and dietary principles, is expected to facilitate weight reduction. Further, adequate time must be made available to the patient to convey the information necessary, to reinforce behavioral and dietary messages, and to monitor the patient's response. Despite these judgments, none of the studies reviewed were designed to specifically address the type or qualifications of the health professional who implemented the various weight loss approaches. Many of the studies differed in the types of
Physical ActivityAn increase in physical activity is an important component of weight loss therapy since it leads to increased expenditure of energy. Increased physical activity may also inhibit food intake in overweight patients. Physical activity can also be helpful in maintaining a desirable weight. In addition, sustained physical activity has the benefit of reducing overall CHD risk beyond that produced by weight reduction alone. Several experts believe that a progressive decrease in the amount of energy expended for work, transportation, and personal chores is a major cause of obesity in the United States. These authorities note that total caloric intake has not increased over the last few decades; instead, the caloric imbalance leading to overweight and obesity is the result of a substantial decrease in physical activity and, consequently, a decrease in daily energy expenditure. However, this hypothesis is difficult to prove because appropriate data are lacking. Successful restoration of normal weight in many overweight and obese persons requires a higher level of energy expenditure. Increased regular physical activity is the way to achieve this goal of augmenting daily energy expenditure.
Evidence Statement: Physical activity contributes to weight loss, both alone and when it is combined with dietary therapy. Evidence Category A. Rationale: Increased physical activity alone can create a caloric deficit and can contribute to weight loss. However, efforts to achieve weight loss through physical activity alone generally produce an average of a 2 to 3 percent decrease in body weight or BMI. Even so, increased physical activity is a useful adjunct to LCDs in promoting weight reduction. Evidence Statement: Physical activity in overweight and obese adults increases cardiorespiratory fitness independent of weight loss. Evidence Category A. Rationale: There is strong evidence that increased physical activity increases cardiorespiratory fitness, with or without weight loss. Improved cardiovascular fitness also improves the quality of life in overweight patients by improving mood, self-esteem, and physical function in daily activities. Evidence Statement: Physical activity independently reduces CVD risk factors (Evidence Category A), and reduces risk for cardiovascular disease. Evidence Category C. Rationale: There is considerable evidence that physical inactivity is an independent risk factor for CVD and diabetes. Furthermore, the more active an individual is, the lower the risk. By the same token, increased physical activity appears to independently reduce risk for CVD morbidity and mortality, and diabetes. Physical activity reduces elevated levels of CVD risk factors, including blood pressure and triglycerides, increases HDL-cholesterol, and improves glucose tolerance with or without weight loss. Evidence Statement: Physical activity contributes to a decrease in body fat, including a modest effect on abdominal fat. Evidence Category B. Rationale: Physical activity appears to have a favorable effect on distribution of body fat. Several large cross-sectional studies in Europe, Canada, and the United States showed an inverse association between energy expenditure through physical activity and several indicators of body fat distribution, such as WHR and waist-to-thigh circumference ratio. Fewer data are available on the effects of physical activity on waist circumference, although the ratio changes noted above suggest a decrease in abdominal obesity. Only a few randomized controlled trials that have tested the effect of physical activity on weight loss measured waist circumference. In some (but not all) studies, physical activity was found to produce only modest weight loss and decreased waist circumference. However, it is not known whether the effects of physical activity on abdominal fat are independent of weight loss. Strategies to Increase Physical activityMany people live sedentary lives, have little training or skills in physical activity, and are difficult to motivate toward increasing their activity. For these reasons, starting a physical activity regimen may require supervision for some people. The need to avoid injury during physical activity is high. Extremely obese persons may need to start with simple exercises that can gradually be intensified. The practitioner must decide whether exercise testing for cardiopulmonary disease is needed before embarking on a new physical activity regimen. This decision should be based on a patient's age, symptoms, and concomitant risk factors. For most obese patients, physical activity should be initiated slowly, and the intensity should be increased gradually. Initial activities may be walking or swimming at a slow pace. With time, depending on progress, the amount of weight lost, and functional capacity, the patient may engage in more strenuous activities. Some of these include fitness walking, cycling, rowing, cross-country skiing, aerobic dancing, and rope jumping. Jogging provides a high-intensity aerobic exercise, but can lead to orthopedic injury. If jogging is desired, the patient's ability to do this must first be assessed. The availability of a safe environment for the jogger is also a necessity. Competitive sports, such as tennis and volleyball, can provide an enjoyable form of physical activity for many, but again, care must be taken to avoid injury, especially in older people. As the examples listed in Table 5 show, a moderate amount of physical activity can be achieved in a variety of ways. People can select activities that they enjoy and that fit into their daily lives. Because amounts of activity are functions of duration, intensity, and frequency, the same amounts of activity can be obtained in longer sessions of moderately intense activities (such as brisk walking) as in shorter sessions of more strenuous activities (such as running). A regimen of daily walking is an attractive form of physical activity for many people, particularly those who are overweight or obese. The patient can start by walking 10 minutes, 3 days a week, and can build to 30 to 45 minutes of more intense walking at least 5 days a week and preferably most, if not all, days.577, 578 With this regimen, an additional 100 to 200 calories per day of physical activity can be expended. Caloric expenditure will vary depending on the individual's body weight and intensity of the activity (see Table 6). This regimen can be adapted to other forms of physical activity, but walking is particularly attractive because of its safety and accessibility.
This regimen can be adapted to other forms of physical activity, but walking is particularly attractive because of its safety and accessibility. With time, a larger weekly volume of physical activity can be performed that would normally cause a greater weight loss if it were not compensated by a higher caloric intake. Reducing sedentary time is another approach to increasing activity. Patients should be encouraged to build physical activities into each day. Examples include leaving public transportation one stop before the usual one, parking further than usual from work or shopping, and walking up stairs instead of taking elevators or escalators. New forms of physical activity should be suggested, e.g., gardening, walking a dog daily, or new athletic activities. Engaging in physical activity can be facilitated by identifying a safe area to perform the activity, e.g., community parks, gyms, pools, and health clubs. However, when these sites are not available, an area of the home can be identified and perhaps outfitted with equipment such as a stationary bicycle or a treadmill. Health professionals should encourage patients to plan and schedule physical activity 1 week in advance, budget the time necessary to do it, and document their physical activity by keeping a diary and recording the duration and intensity of exercise. Recommendation: Physical activity should be an integral part of weight loss therapy and weight maintenance. Evidence Category A. Initially, moderate levels of physical activity for 30 to 45 minutes, 3 to 5 days per week should be encouraged. All adults should set a long-term goal to accumulate at least 30 minutes or more of moderate-intensity physical activity on most, and preferably all, days of the week. Evidence Category B. Behavior therapyBehavioral strategies to reinforce changes in diet and physical activity can produce a weight loss in obese adults in the range of 10 percent of baseline weight over 4 months to 1 year. Unless a patient acquires a new set of eating and physical activity habits, long-term weight reduction is unlikely to succeed. The acquisition of new habits is particularly important for long-term weight maintenance at a lower weight. Most patients return to baseline weights in the absence of continued intervention. Thus, the physician or staff members must become familiar with techniques for modifying life habits of overweight or obese patients. The goal of behavior therapy is to alter the eating and activity habits of an obese patient. Techniques for behavior therapy have been developed to assist patients in modifying their life habits. Evidence Statement: Behavior therapy, in combination with an energy deficit, provides additional benefits in assisting patients to lose weight short-term (1 year). Its effectiveness for long-term weight maintenance has not been shown in the absence of continued behavioral intervention. Evidence Category B. Rationale: The primary assumptions of behavior therapy are that:
Behavior therapies provide methods for overcoming barriers to compliance with dietary therapy and/or increased physical activity, and are thus important components of weight loss therapy. Most weight loss programs incorporating behavioral strategies do so as a package that includes education about nutrition and physical activity. However, this standard "package" of management should not ignore the need for individualizing behavioral strategies. Behavior therapy strategies used in weight loss and weight maintenance programsStudies reviewed for this report examined a range of modalities of behavioral therapy. No single method or combination of behavioral methods proved to be clearly superior. Thus, various strategies can be used by the practitioner to modify patient behavior. The aim is to change eating and physical activities behaviors over the long term. Such change can be achieved either on an individual basis or in group settings. Group therapy has the advantage of lower cost. Specific behavioral strategies include the following:
Treatment of Obese Individuals With Binge Eating DisorderIf a patient suffers from binge eating disorder (BED), consideration can be given to referring the patient to a health professional who specializes in BED treatment. Behavioral approaches to BED associated with obesity have been derived from cognitive behavior therapy (CBT) used to treat bulimia nervosa. Among the techniques are self-monitoring of eating patterns, encouraging regular patterns of eating (three meals a day plus planned snacks), cognitive restructuring, and relapse prevention strategies. Recommendation: Behavior therapy strategies to promote diet and physical activity should be used routinely, as they are helpful in achieving weight loss and weight maintenance. Evidence Category B. Combined therapyTo achieve the greatest likelihood of success from weight loss therapy, the combination of dietary therapy with an LCD, increased physical activity, and behavior therapy will be required. Inclusion of behavior therapy and increased physical activity in a weight loss regimen will provide the best opportunity for weight loss, and hopefully for long-term weight control. In order to achieve weight loss, such a regimen should be maintained for at least 6 months before considering pharmacotherapy. Evidence Statement: Combined intervention of an LCD, increased physical activity, and behavior therapy provides the most successful therapy for weight loss and weight maintenance. Evidence Category A. Rationale: Clinical trials have demonstrated that combining behavior therapy, LCDs, and increased physical activity provides better outcomes for long-term weight reduction than programs that use only one or two of these modalities. A lower-fat diet markedly improves the potential of physical activity to achieve a negative energy balance. In addition, lower-fat diets that are also low in saturated fats reduce serum cholesterol levels, which would reduce CVD risk. It is difficult to achieve a negative energy balance and weight loss with physical activity of moderate duration and intensity in individuals who consume a high-fat diet and alcohol. Recommendation: Weight loss and weight maintenance therapy should employ the combination of LCDs, increased physical activity, and behavior therapy. Evidence Category A. PharmacotherapyDrug therapy has undergone radical changes in the last 2 years. With the publication of the trials with phentermine and fenfluramine by Weintraub in 1992 (210 weeks), drug therapy began to change from short-term to long-term use. Both dexfenfluramine and fenfluramine alone, as well as the combination of phentermine/ fenfluramine, were used long term. However, concerns about recently reported unacceptable side effects, such as valvular lesions of the heart causing significant insufficiency of the valves, have led to the withdrawal of the drugs dexfenfluramine and fenfluramine from the market in September 1997. No drugs remained that were approved by the Food and Drug Administration (FDA) for use longer than 3 months. In November 1997, the FDA approved a new drug, sibutramine, for use in obesity and is in the process of evaluating or list at for long-term use. Evidence Statement: Appropriate weight loss drugs can augment diet, physical activity, and behavior therapy in weight loss. Evidence Category B. Rationale: The purpose of weight loss and weight maintenance is to reduce health risks. If weight is regained, health risks increase once more. The majority of persons who lose weight regain it, so the challenge to the patient and the practitioner is to maintain the weight loss. Because of the tendency to regain weight after weight loss, the use of long-term medication to aid in the treatment of obesity may be indicated in carefully selected patients. The drugs used to promote weight loss have been anorexiants or appetite suppressants. Three classes of anorexiant drugs have been developed, all of which affect neurotransmitters in the brain: those that affect catecholamines, those that affect serotonin, and those that affect both. They work by increasing the secretion of dopamine, norepinephrine, or serotonin into the synaptic neural cleft, or by inhibiting the reuptake of these neurotransmitters back into the neuron, or by both mechanisms. The new agent sibutramine has norepinephrine and serotonin effects. Another new agent, orlistat, has a different mechanism of action, the blockage of fat absorption. Very few trials longer than 6 months have been done with any drug. The ones tested for at least 1 year that received FDA approval for long-term use are shown in Table 7. These drugs are effective but modest in their ability to produce weight loss. Net weight loss attributable to drugs generally has been reported to be in the range of 2 to 10 kg (4.4 to 22 lb), although some patients lose significantly more weight. It is not possible to predict how much weight an individual may lose. Most of the weight loss usually occurs in the first 6 months of therapy. Adverse effects include primary pulmonary hypertension with fenfluramine and dexfenfluramine, valvular heart disease with dexfenfluramine and fenfluramine, and increases in blood pressure and pulse with sibutramine. With orlistat, there is a possible decrease in the absorption of fat-soluble vitamins; overcoming this may require vitamin supplementation. People with a history of high blood pressure, CHD, congestive heart failure, arrhythmias, or history of stroke should not take sibutramine, and all patients taking the medication should have their blood pressure monitored on a regular basis. Depression has been described with the serotonergic drugs but it is generally not clinically significant. Neurotoxic effects with neuronal atrophy have been described with high doses of dexfenfluramine in rats and primates, but not in humans. The risks for using appetite suppressant drugs during pregnancy is unknown.
Evidence Statement: Weight loss drugs approved by the FDA for long-term use may be useful as an adjunct to diet and physical activity for patients with a BMI of ³ 30 with no concomitant obesity-related risk factors or diseases, and for patients with a BMI of ³ 27 with concomitant obesity-related risk factors or diseases. Evidence Category B. Rationale: If after at least 6 months on a weight loss regimen of an LCD, increased physical activity, and behavior therapy, the patient has not lost the recommended 1 lb/week, careful consideration may be given to pharmacotherapy. There are few long-term studies evaluating the safety or effectiveness of many currently approved weight loss medications. At present, sibutramine is available for long-term use. (Note: FDA approval for orlistat is pending a resolution of labeling issues and results of Phase III trials.) Their risk/benefit ratio is such that they can be recommended for use with the degree of obesity outlined above. Weight loss medications should be used only by patients who are at increased medical risk because of their weight and should not be used for "cosmetic" weight loss. The risk factors and diseases considered serious enough to warrant pharmacotherapy at BMI of 27 to 29.9 are hypertension, dyslipidemia, CHD, type 2 diabetes, and sleep apnea. Not every patient responds to drug therapy. Tests with weight loss drugs have shown that initial responders tend to continue to respond, while initial nonresponders are less likely to respond even with an increase in dosage. If a patient does not lose 2 kg (4.4 lb) in the first 4 weeks after initiating therapy, the likelihood of long-term response is very low. This finding may be used as a guide to treatment, either continuing medication in the responders or stopping it in the nonresponders. If weight is lost in the initial 6 months of therapy or is maintained after the initial weight loss phase, this should be considered a success, and the drug may be continued. It is important to remember that the major role of medications should be to help patients stay on a diet and physical activity plan while losing weight. Medication cannot be expected to continue to be effective in weight loss or weight maintenance once it has been stopped. The use of the drug may be continued as long as it is effective and the adverse effects are manageable and not serious. There are no indications for specifying how long a weight loss drug should be continued. Therefore, an initial trial period of several weeks with a given drug or combination of drugs may help determine their efficacy in a given patient. If a patient does not respond to a drug with reasonable weight loss, the physician should reassess the patient to determine adherence to the medication regimen and adjunctive therapies, or consider the need for dosage adjustment. If the patient continues to be unresponsive to the medication, or serious adverse effects occur, the physician should consider its discontinuation. Evidence Statement: Adverse side effects from the use of weight loss drugs have been observed in patients. Evidence Category A. Rationale: The potential for side effects from the use of weight loss drugs is of great concern. Adverse effects with sibutramine include increased blood pressure and tachycardia. With orlistat there are oily and loose stools and some fat-soluble vitamin malabsorption. Thus, a multivitamin supplement is recommended. Side effects are generally mild and may improve with continued use, although their persistence may result in discontinuation of the drug. There is a great interest in weight loss drugs among consumers. Because of the possibility of serious adverse effects, it is incumbent on the practitioner to use drug therapy with caution. Practitioners should be sure that patients are not taking drugs that have been withdrawn from the market for safety reasons, and herbal medications are not recommended as part of a weight loss program. These preparations have unpredictable amounts of active ingredients and unpredictable and potentially harmful effects. In those patients with a lower level of obesity risk, non-pharmacological therapy is the treatment of choice. It is important for the physician to monitor both the effectiveness and the side effects of the drug. Evidence Statement: Using weight loss drugs singly (not in combination) and starting with the lowest effective doses can decrease the likelihood of adverse effects. Evidence Category C. Rationale: Given the fact that adverse events may increase in association with combination drug therapy, it seems wise that, until further safety data are available, using weight loss drugs singly would be more prudent. Some patients will respond to lower doses, so that full dosage is not always necessary. The short-term use of drugs (< 3 months) has not generally been found to be effective. Drugs should be used only as part of a comprehensive program that includes behavior therapy, diet, and physical activity. Appropriate monitoring for side effects must be continued while drugs are part of the regimen. Patients will need to return for follow up in 2 to 4 weeks, then monthly for 3 months, and then every 3 months for the first year after starting the medication. After the first year, the doctor will advise the patient on appropriate return visits. The purposes of these visits are to monitor weight, blood pressure, and pulse, discuss side effects, conduct laboratory tests, and answer questions. Since obesity is a chronic disorder, the short-term use of drugs is not helpful. The health professional should include drugs only in the context of a long-term treatment strategy. The risk/benefit ratio cannot be predicted at this time, since not enough long-term data (> 1 year) are available on any of the available drugs.
Surgery for weight LossSurgery is one option for weight reduction for some patients with severe and resistant obesity. The aim of surgery is to modify the gastrointestinal tract to reduce net food intake. Most authorities agree that weight loss surgery should be reserved for patients with severe obesity, in whom efforts at other therapy have failed, and who are suffering from the complications of obesity. Considerable progress has been made in developing safer and more effective surgical procedures for promoting weight loss. Surgical interventions commonly used include gastroplasty, gastric partitioning, and gastric bypass. These procedures are designed primarily to reduce food consumption. They have replaced previous procedures that were designed to promote malabsorption of nutrients. The latter procedures were fraught with side effects that made their use impractical or dangerous. Evidence Statement: Gastrointestinal surgery (gastric restriction [vertical gastric banding] or gastric bypass [Roux-en Y]) can result in substantial weight loss, and therefore is an available weight loss option for well-informed and motivated patients with a BMI ³ 40 or ³ 35, who have comorbid conditions and acceptable operative risks. Evidence Category B. Rationale: According to the National Institutes of Health's Consensus Development Conference on Gastrointestinal Surgery for Severe Obesity, the risk for morbidity and mortality accompanying obesity increases with the degree of overweight. Thus, treatment of clinically severe obesity involves an effort to create a caloric deficit sufficient to result in weight loss and reduction of weight-associated risk factors or comorbidities. Surgical approaches can result in substantial weight loss, i.e., from 50 kg (110 lb) to as much as 100 kg (220 lb) over a period of 6 months to 1 year. A major limitation of nonsurgical approaches is the failure to maintain reduced body weight in many individuals. Surgical procedures in current use (gastric restriction [vertical gastric banding] and gastric bypass [Roux-en Y]) can induce substantial weight loss, and serve to reduce weight-associated risk factors and comorbidities. Compared to other interventions available, surgery has produced the longest period of sustained weight loss. Assessing both perioperative risk and longterm complications is important and requires assessing the risk/benefit ratio in each case. Patients whose BMI equals or exceeds 40 kg/mare potential candidates for surgery if they strongly desire substantial weight loss, because obesity severely impairs the quality of their lives. Less severe obese patients (BMIs between 35 and 39.9 kg/m) also may be considered for surgery. This group primarily includes those patients with high-risk comorbid conditions (cardiovascular, sleep apnea, uncontrolled type 2 diabetes) or weight-induced physical problems interfering with performance of daily life activities. A recent retrospective study of severely overweight patients with noninsulin-dependent diabetes, who were referred for consideration of a gastric bypass procedure, allowed for a comparison of those who opted for the surgical procedure versus those who did not undergo the procedure because of personal preference or refusal of insurance payment. Patients undergoing the surgical procedure had a decrease in mortality rate for each year of follow up. This latter observation provides initial documentation of the significant impact that reduction in weight may have on mortality. Most of the surgery studies primarily included women of childbearing age. Caution should be exercised in selecting candidates for surgery to treat obesity, as pregnancy demands increase nutritional needs and a normal need for weight gain. Women with reproductive potential should be advised to avoid pregnancy until their weight has stabilized postoperatively and potential micronutrient deficiencies have been identified and treated. Of special note is that many of the studies reported to date have not had population samples representative of the general severely overweight population with respect to race, ethnicity, cultural or socioeconomic background, or gender. Evidence Statement: Patients opting for surgical intervention should be followed by a multidisciplinary team (medical, behavioral, and nutritional). Evidence Category D. Rationale: As for all other interventions for obesity, an integrated program should be in place that will provide guidance concerning the necessary dietary regimen, appropriate physical activity, and behavioral and social support both prior to and after the surgical procedure. Evidence Statement: Lifelong medical surveillance after surgical therapy is a necessity. Evidence Category C. Rationale: Since surgical procedures result in some loss of absorptive function, the long-term consequences of potential nutrient deficiencies must be recognized and adequate monitoring must be performed, particularly with regard to vitamin B, folate, and iron. Some patients may develop other gastrointestinal symptoms such as "dumping syndrome" or gallstones. Occasionally, patients may have postoperative mood changes or their presurgical depression symptoms may not be improved by the achieved weight loss. Thus, surveillance should include monitoring of indices of inadequate nutrition and modification of any preoperative disorders. Table 8 illustrates some of the complications that can occur following gastric bypass surgery.
Recommendation: Weight loss surgery is an option for carefully selected patients with clinically severe obesity (BMI ³ 40 or ³ 35 with comorbid conditions) when less invasive methods of weight loss have failed and the patient is at high risk for obesity-associated morbidity or mortality. Evidence Category B. Adapting Weight Loss Programs To Meet the Needs of Diverse Patient PopulationsStandard obesity treatment approaches should be tailored to the needs of patients. It is, however, difficult to determine from the literature how often this occurs and whether it makes weight loss programs more effective. Very few published reports of such adapted programs can be identified, particularly when a distinction is made from reports that include or focus on special populations but do not report any particular steps taken to modify the intervention for these populations. In addition, it is impossible to compare directly the amount of weight lost using specially adapted programs with that achieved when more standard approaches are used. Studies reporting these programs are sometimes pilot studies or descriptive reports that do not meet the standards of evidence set forth elsewhere in these guidelines. Where randomized controlled trials or quasi-experiments are available, they usually do not include an internal comparison with a program involving no adaptations. Appendix III illustrates the types of adaptations that have been reported. Large individual variation exists within any social or cultural group; furthermore, there is substantial overlap among subcultures within the larger society. There is, therefore, no "cookbook" or standardized set of rules to optimize weight reduction with a given type of patient. A theoretical and qualitative analysis of cultural appropriateness in obesity treatment programs has been conducted, and it provides some guidance for incorporating patient characteristics and perspectives when designing and delivering weight loss programs. Some examples follow:
The staff should be culturally self-aware and culturally competent in working with persons of diverse cultural backgrounds and income or educational levels. For example, cultural adaptation of programs has been approached with the assumption that community centers may be preferable to hospitals or medical offices as venues for conducting lifestyle weight reduction programs. Or, some programs have included peer educators as a possible way of helping to overcome background and social class differences by providing a bridge of knowledge, experience, and perspective between patients and practitioners.
In recent years, a fat acceptance, non-dieting advocacy group has developed. This has emerged from concerns about weight cycling and its possible adverse effects on morbidity and mortality. However, recent evidence suggests that intentional weight loss is not associated with increased morbidity and mortality. For this reason, the guidelines have been made explicit on the importance of intervention for weight loss and maintenance in the appropriate patient groups. Weight Reduction After Age 65 - What Are The Issues?Are the indications for treating obesity in older adults the same as those for younger adults?
The higher prevalence of cardiovascular risk factors in overweight versus non overweight persons is clearly observed at older ages. In addition, obesity is a major predictor of functional limitations and mobility impairments in older adults. Both observational data and applicable randomized controlled trials cited in these guidelines suggest that weight loss reduces risk factors and improves functional status in older persons in the same manner as in younger adults. The question of whether weight reduction leads to increased survival among older adults has been raised because of observations that weight reduction after age 60 or 65 years may be unable to reverse the deleterious effects of longstanding obesity. Also, weight loss at older ages has been associated with increased mortality. Some of the association of weight loss with higher mortality may be due to the increased frequency at older ages of involuntary weight loss due to identified or occult illness. In any case, the association of weight loss with higher mortality applies most clearly to individuals who enter old age with a BMI in the lower part of the range. It is not clear that it applies to overweight older persons with CVD risk factors. This issue has been difficult to clarify in observational data, but there are no randomized trials in which the effects of obesity treatment on mortality can be directly assessed, at any age. The wisdom or importance of treating obesity at older ages has also been questioned because of epidemiological observations suggesting a decreased significance of obesity-related relative risks at older ages. However, these relative risk data are not a useful reference point for considering whether obese older persons will benefit. Relative risks are influenced by the characteristics of the comparison group. In this case, the comparison group is lower-weight older persons who have also had high morbidity and mortality. Concerns about potential adverse effects of obesity treatment in older adults have been raised with respect to bone health and to dietary adequacy. Weight reduction may accelerate aging-related bone loss and thereby increase the risk of osteoporotic fractures in high-risk groups such as older white women. This concern is more relevant to weight loss in thin persons than in obese persons. Some evidence suggests that including resistance training and moderate weight-bearing exercise as a part of a weight reduction program may help maintain bone integrity. The general nutritional safety of weight reduction at older ages is of interest because restrictions on overall food intake due to dieting could result in inadequate intakes of protein or essential vitamins and minerals. In addition, involuntary weight loss indicative of occult disease might be mistaken for success in voluntary weight reduction. These concerns can be alleviated by providing proper nutritional counseling and regular body weight monitoring for older persons for whom weight reduction is prescribed. Evidence Statement: Age alone should not preclude treatment for obesity in adult men and women. Evidence Category D. Rationale: There is little evidence at present to indicate that obesity treatment should be withheld from adult men and women on the basis of age alone up to 80 years of age. Recommendation: A clinical decision to forego obesity treatment in an older adult should be guided by an evaluation of the potential benefits of weight reduction for day-to-day functioning and reduction of the risk of future cardiovascular events, as well as the patient's motivation for weight reduction. Care must be taken to ensure that any weight reduction program minimizes the likelihood of adverse effects on bone health or other aspects of nutritional status. Evidence Category D.
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Smoking Cessation in the Overweight or Obese PatientCigarette smoking is a major risk factor for cardiopulmonary disease. Because of its attendant high risk, smoking cessation is a major goal of risk-factor management. This aim is especially important in the overweight or obese patient, who usually carries excess risk from obesity-associated risk factors. Thus, smoking cessation in such patients becomes a high priority for risk reduction. Evidence Statement: Smoking and obesity together increase cardiovascular risk, but fear of weight gain upon smoking cessation is an obstacle for many patients who smoke. Evidence Category C. Rationale: Both smoking and obesity are accompanied by increased risks for cardiovascular disease. Many well-documented health benefits are associated with smoking cessation, but a major obstacle to successful smoking cessation has been the attendant weight gain observed in about 80 percent of quitters. This weight gain averages 4.5 to 7 lb, but in 13 percent of women and 10 percent of men, weight gains in excess of 28 lb have been noted among quitters. Weight gain is an important barrier to smoking cessation, particularly in women. Weight gain that accompanies smoking cessation so far has been relatively resistant to most dietary, behavioral, or physical activity interventions. Postcessation weight gain has been associated with a reduction in energy expenditure of up to 100 kcal/day, accounting for approximately one-third of the weight gain after smoking cessation. The reduction in energy expenditure appears to be the result of a decrease in the resting metabolic rate. In general, no differences in the level of physical activity have been observed after smoking cessation. About two-thirds of the weight gain after smoking cessation appears to result from increased caloric intake. However, dietary counseling programs combined with smoking cessation programs have not been very successful. There are several products that reduce postcessation weight gain during drug administration, including nicotine replacement therapy, phenylpropanolamine, and bupropion. No matter what the drug, however, it appears that these drugs merely delay rather than prevent postcessation weight gain. That is, while providing weight gain suppression during drug administration, subjects on these drugs experience a rebound of weight gain once they go off the products and long-term weight gain is equal to that in those not receiving these drugs. The weight gained with smoking cessation is less likely to produce negative health consequences than would continued smoking. For this reason, smoking cessation should be strongly reinforced in persons regardless of their baseline weight. Smoking is not an acceptable weight control therapy, although it seems to be used for this purpose by a great many people. Overweight patients, as well as all others, should be counseled to quit smoking. For practical reasons, it may be prudent to avoid initiating smoking cessation and weight loss therapy simultaneously. Prevention of weight gain through diet and physical activity should be stressed. If weight gain ensues after smoking cessation, it should be managed vigorously according to the guidelines outlined in this report. Although short-term weight gain is a common side effect of smoking cessation, this gain does not rule out the possibility of long-term weight control. There are no clinical trials to test whether ex-smokers are less likely to successfully achieve long-term weight reduction than those who never smoked. Recommendation: All smokers, regardless of their weight status, should quit smoking. Evidence Category A. Prevention of weight gain should be encouraged and if weight gain does occur, it should be treated through dietary therapy, physical activity, and behavior therapy, maintaining the primary emphasis on the abstinence from smoking. Evidence Category C. |
Role of Health Professionals in Weight Loss TherapyEvidence Statement: A number of health professionals can play an important role in a weight loss and management program. Evidence Category B. Rationale: Various randomized controlled trials were reviewed that highlighted the role of the nutritionists, exercise physiologists and physical education instructors, nurses, and psychologists in addition to the physician in providing assessment, treatment, and follow up during weight loss. As a result, it is suggested that the health professionals avail themselves of the various disciplines that offer expertise in dietary counseling, physical activity, and behavior change. The relationship between the physician and these disciplines can be a direct, formal one or a more indirect referral. It is important to emphasize that a positive attitude of support and encouragement from all professionals is crucial to continuing success. Recommendation: A weight loss and maintenance program can be conducted by a practitioner without specialization in weight loss so long as that person has the requisite interest and knowledge. However, various health professionals with different expertise are available and helpful to a practitioner who would like assistance. Evidence Category B. |
Obesity and Sleep ApneaObstructive sleep apnea is defined as an absence of breathing during sleep. Currently, it is recognized that sleep apnea is part of a continuum from health to disease. Apnea is currently defined as cessation of airflow for at least 10 seconds and is characterized as either central (if no respiratory effort occurs), obstructive (if continued effort is noted), or mixed (if both central and obstructive components are present). Apnea is associated with either a fall in oxyhemoglobin desaturation or an arousal from sleep. Hypopneas, which are defined as partial reductions in airflow associated with falls in oxygen saturation or arousals from sleep, are also recorded. The sleep apnea syndrome has been clinically defined as recurrent apnea or hypopnea associated with clinical impairment usually manifested as increased daytime sleepiness or altered cardiopulmonary function. In general, the average number of episodes of apnea and hypopnea per hour are reported as an index (AHI) or as a respiratory disturbance index (RDI). Classically, an AHI of greater than five episodes per hour has been the definition of the presence of the sleep apnea syndrome. Other commonly used cutoff points are an AHI of 10 or 15 episodes per hour or an overnight total of 30 apneichypopneic episodes. There are several correlates of sleep apnea. It is well recognized that it is more prevalent in males, although the difference is less pronounced in population-based studies than in laboratory-based studies. Some studies have suggested that the prevalence of sleep apnea in women increases after menopause. Snoring also correlates with sleep apnea, increasing up to late middle age and decreasing thereafter. The other major correlate of sleep apnea is obesity in both men and women. In general, women have to be significantly more obese than men for the clinical syndrome to be apparent. At present, no published epidemiologic studies have examined the relationship between race and sleep apnea. Given the high prevalence of obesity among specific populations and minorities, sleep apnea may be highly prevalent in these groups. The major pathophysiologic consequences of severe sleep apnea include severe arterial hypoxemia, recurrent arousals from sleep, increased sympathetic tone, pulmonary and systemic hypertension, and cardiac arrhythmias. These phenomena may result in acute hemodynamic and chronic structural change in the coronary arteries, possibly associated with relative myocardial ischemia, rupture of atheromatous plaques, and increased risk for thrombosis at the site of any unstable plaque. Similar mechanisms acting in the cerebrovascular system may be involved in an increased risk of stroke. Finally, the sympathetic tone may be associated with hypertension as well as increased platelet aggregability. The primary goal for treatment of individuals with sleep apnea is to reduce the severity of the respiratory events that are associated with oxyhemoglobin desaturation and arousal from sleep. There are only two cohort studies in clinic-based populations that demonstrate a significant reduction in cardiovascular mortality among sleep apnea patients who are treated progressively compared to those who are treated conservatively. However, both of these studies were retrospective and suffered from a significant bias of ascertainment. The evidence that treatment of obesity ameliorates obstructive sleep apnea is reasonably well established. Although the studies are small, both surgical and medical approaches to weight loss have been associated with a consistent but variable reduction in the number of respiratory events, as well as improvement in oxygenation. In general, surgical interventions, which have included a gastric bypass or jejunoileostomy, have been reserved for people who are severely obese. While this approach to weight reduction was commonly used in patients with severe obstructive sleep apnea, they recently have been abandoned because of complications and side effects. However, the use of surgical gastric procedures has been successful in improving sleep apnea in a number of studies. On the other hand, weight reduction has been associated with comparable reduction in the severity of sleep apnea, as well as improved evidence of renal function and hypertension Both medical and surgical studies have demonstrated that as little as 10-percent weight reduction is associated with a more than 50-percent reduction in the severity of sleep apnea. Moreover, more recent data suggest a possible "threshold" effect that is directly related to the collapsibility of the upper airway. Those individuals who demonstrate a minimally collapsible upper airway apparently achieve a greater effect for the same percentage of weight reduction. Finally, there is evidence that standard treatments for sleep apnea do reduce specific cardiovascular risk factors. Specifically, the most commonly employed treatment, continuous positive airway pressure, has been shown to reduce waking arresting carbon dioxide and reduced heart rate, and pulmonary artery pressure decreased hematocrit and improved ventricular ejection fraction. Other standard surgical approaches that have been employed to widen the upper airway have been shown to reduce the severity of the apnea, but there are no data examining the associated cardiovascular risk factors. No studies have specifically examined the effects of treatment of sleep apnea on obesity, but it generally has been noted that all non-weight loss treatments of sleep apnea have not been associated with any significant weight loss other than might be accrued from surgical interventions that temporarily reduce the ability to eat in the immediate postoperative period. |