Obesity in adults: Overview of management

INTRODUCTION — The morbidity and mortality associated with having overweight or obesity have been known to the medical profession since the time of Hippocrates more than 2500 years ago. Overweight refers to a weight above the "normal" range, with normal defined on the basis of actuarial data. This is determined by calculating the body mass index (BMI, defined as the weight in kilograms divided by height in meters squared). Overweight is defined as a BMI of 25 to 29.9 kg/m²; obesity is defined as a BMI of ≥30 kg/m². Severe obesity is defined as a BMI ≥40 kg/m² (or ≥35 kg/m² in the presence of comorbidities) (calculator 1). Although these categorical definitions are clinically useful, it is clear that the risks imparted by increasing body mass follow a continuum and vary considerably between individuals.

An overview of the management of obesity is provided here. Information on screening, evaluation, health hazards associated with obesity, and specific therapies are reviewed in detail elsewhere.

●(See "Obesity in adults: Prevalence, screening, and evaluation".)

●(See "Overweight and obesity in adults: Health consequences".)

●(See "Obesity in adults: Dietary therapy".)

●(See "Obesity in adults: Role of physical activity and exercise".)

●(See "Obesity in adults: Behavioral therapy".)

●(See "Obesity in adults: Drug therapy".)

●(See "Bariatric procedures for the management of severe obesity: Descriptions".)

●(See "Bariatric surgery for management of obesity: Indications and preoperative preparation".)

●(See "Outcomes of bariatric surgery".)

●(See "Intragastric balloon therapy for weight loss".)

IMPORTANCE OF WEIGHT LOSS — The medical rationale for weight loss in people with obesity is that obesity is a disease associated with a significant increase in mortality (figure 1) and many health risks, including type 2 diabetes mellitus, hypertension, dyslipidemia, and coronary heart disease. The higher the body mass index (BMI), the greater the risk of morbidity and mortality [1]. The relationship between BMI and mortality is likely to be similar for all races and ethnicities, but the minimal BMI where excess risk is seen may differ. These risks are reviewed in detail separately. (See "Overweight and obesity in adults: Health consequences".)

Morbidity — Life insurance reports, the first to suggest that lower body weight was associated with lower morbidity and mortality, have been corroborated by the Behavioral Risk Factor Surveillance System (BRFSS) among other studies [2]. Furthermore, randomized trials inducing weight loss via lifestyle, pharmacologic therapy, or bariatric surgical procedures have been shown to reduce a wide array of weight-related morbidity [1,3-5].

As an example, in the frequently cited Diabetes Prevention Program (DPP), intensive lifestyle modification focusing on weight loss reduced the rate of progression from impaired glucose tolerance to diabetes over three years [6]. The efficacy of the intensive lifestyle modification persisted over 15 years but was somewhat attenuated over time. There was also a persistent reduction in risk factors for cardiovascular disease (CVD) [7,8], although no reduction was observed for all-cause, cancer-related, or cardiovascular mortality at 21 years of follow-up [9]. In similar trials evaluating intensive clinician-supervised weight loss, remission of type 2 diabetes was reported in approximately 50 percent of patients [10,11].

Other trials have also reported a beneficial effect of weight loss on additional CVD risk factors, including blood pressure [12,13] and plasma lipid levels [14], as well as a reduction in cardiovascular events [15], although the latter was only seen after bariatric surgery. Additional benefits of weight loss include improvements in urinary incontinence, sleep apnea, depression, quality of life, physical functioning, and mobility. (See "Obesity: Association with cardiovascular disease", section on 'Benefits of weight loss' and "Overweight, obesity, and weight reduction in hypertension", section on 'Long-term effects of weight reduction' and "Overweight and obesity in adults: Health consequences", section on 'Morbidity'.)

Mortality — Evidence from observational studies and randomized trials suggest that weight loss (including nonsurgical and surgical weight loss approaches) in people with overweight and obesity is associated with a reduction in overall mortality [13,16-20]. (See "Outcomes of bariatric surgery".)

In the Look AHEAD (Action for Health in Diabetes) trial, 5145 individuals with type 2 diabetes and BMI >25 kg/m² were randomly assigned to an intensive lifestyle intervention (group and individual meetings to achieve weight loss with diet and exercise) or standard diabetes education [21]. After a median follow-up of 9.6 years, the composite primary outcome (death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for angina) occurred in a similar number of patients in the intervention and control groups [22]. Possible reasons for this finding include the lower-than-expected rates of cardiovascular events in both groups, improved overall cardiovascular risk factor treatment with medical therapy (eg, antihypertensives, statins), enrollment of a relatively healthy patient population, and gradual weight loss in the control group such that the differential weight loss between the two groups was only 2.5 percent at study end [23]. However, among those trial participants who lost >10 percent of their weight over the first year, there was a 20 percent risk reduction in the primary composite outcome [3]. Furthermore, the intervention group achieved its results with less use of CVD risk-lowering medications than the control group.

APPROACH TO THERAPY — The approach to management outlined below is based upon available clinical trial evidence (reviewed in the individual topics), clinical expertise, and patient preference, and is largely in agreement with published guidelines [24].

Goals of treatment — The goal of therapy is to prevent, treat, or reverse the complications of obesity and improve quality of life [24,25]. Health benefits have been reported with weight loss of as little as 5 percent of body weight [6]. Many patients, however, have a weight loss goal of 30 percent or more below their current weight, a goal that is often not achievable without bariatric surgery. With lifestyle measures alone, a weight loss of 5 to 7 percent of body weight is more typical but often difficult to maintain. In trials comparing pharmacologic therapy with placebo, weight loss of 5 to 10 percent using both drug and behavioral intervention is considered a very good response, and weight loss exceeding 10 percent is considered an excellent response. Hence, it is helpful to understand the expected magnitude of weight loss with any given intervention in order to align it with the patient's goal. Of note, in a randomized trial, treatment with semaglutide resulted in an 14.9 percent average weight loss, with roughly one-third of patients achieving ≥ 20 percent weight loss at one year [26]. These results suggest that developments in pharmacotherapies may ultimately yield weight loss results approaching those seen in bariatric surgery.

Identify candidates — Assessment of an individual's overall risk status includes determination of the degree of overweight (body mass index [BMI]), the presence of abdominal obesity (waist circumference), and the presence of cardiovascular disease (CVD) risk factors (eg, hypertension, diabetes, dyslipidemia) or other comorbidities (eg, sleep apnea, nonalcoholic fatty liver disease). The relationship between BMI and risk for weight-related health complications allows identification of patients appropriate for weight loss intervention. (See "Obesity in adults: Prevalence, screening, and evaluation", section on 'Assessing obesity-related health risk'.)

●Little or no risk – A BMI of 20 to 25 kg/m² is associated with little or no increased risk unless waist circumference is high (a marker of increased cardiometabolic risk) or the person has gained more than 10 kg since age 18 years. Asian individuals start to incur risk, even in this low range (ie, BMI >23 kg/m²). (See "Obesity in adults: Prevalence, screening, and evaluation", section on 'BMI-based classifications'.)

●Low risk – Individuals with a BMI of 25 to 29.9 kg/m², who do not have risk factors for CVD or other weight-related comorbidities, may be described as having low risk, particularly if they are older. They should receive counseling on prevention of weight gain, including advice on dietary habits and physical activity. (See "Obesity in adults: Behavioral therapy".)

●Moderate risk – Individuals with a BMI between 25 and 29.9 kg/m² and with one or more risk factors for CVD (diabetes, hypertension, dyslipidemia), or with a BMI of 30 to 34.9 kg/m², are at moderate risk. Such patients should be offered or referred to intensive, multicomponent behavioral intervention [27]. This includes tools and strategies to make dietary changes, increase physical activity, and support and maintain weight loss. Pharmacologic therapy should also be considered.

●High risk – Individuals with a BMI of 35 to 40 kg/m² are at high risk, especially those ages 20 to 39 [28], as well as those with a BMI above 40 kg/m². Individuals in the highest-risk categories should receive the most aggressive treatment (intensive, multicomponent behavioral intervention, pharmacologic therapy, bariatric surgery). (See "Obesity in adults: Behavioral therapy" and "Obesity in adults: Drug therapy" and "Bariatric surgery for management of obesity: Indications and preoperative preparation".)

BMI is calculated as follows:

BMI = Body weight (in kg) ÷ height squared, in meters (calculator 1)

BMI is correlated with body fat. Overweight and obesity are defined as a BMI between 25 and 29.9 kg/m² and a BMI ≥30 kg/m², respectively. As noted, an elevated BMI is a necessary basis for treatment. (See "Obesity in adults: Prevalence, screening, and evaluation", section on 'Body mass index'.)

Waist circumference is measured with a metal or plastic, nondistensible tape measure, placed around the abdomen parallel to the floor at the level of the iliac crest with the patient standing (figure 2). A waist circumference of ≥40 inches (102 cm) for men and ≥35 inches (88 cm) for women is considered elevated and indicative of increased cardiometabolic risk [1]. In the BMI range of 25 to 35 kg/m², an increased waist circumference may indicate need for more aggressive treatment [1]. (See "Obesity in adults: Prevalence, screening, and evaluation", section on 'Waist circumference'.)

However, there is ethnic variability in waist circumference values that predict increased risk. As an example, Japanese Americans and Indians from South Asia have more total fat and visceral fat and therefore may be at higher risk of developing type 2 diabetes for a given BMI than White persons. In Asian females, waist circumference >80 cm (31.5 inches) and in Asian males a value >90 cm (35.4 inches) are considered abnormal. (See "Obesity in adults: Prevalence, screening, and evaluation", section on 'Waist circumference'.)

Initial treatment — The initial management of individuals who would benefit from weight loss is a comprehensive lifestyle intervention: a combination of diet, exercise, and behavioral modification. All patients who would benefit from weight loss should receive counseling on diet, exercise, and goals for weight loss. The behavioral modification component facilitates adherence to diet and exercise regimens, and includes regular self-monitoring of food intake, physical activity, and weight. The role of behavioral therapy, diet, and exercise in the treatment of obesity are reviewed in detail separately. (See "Obesity in adults: Behavioral therapy" and "Obesity in adults: Dietary therapy", section on 'Goals of weight loss' and "Obesity in adults: Role of physical activity and exercise".)

Comprehensive lifestyle intervention — One example of a successful comprehensive lifestyle intervention program is the Diabetes Prevention Program (DPP) [6], subsequently used in the Look AHEAD (Action for Health in Diabetes) study [22]. The two major goals of the DPP lifestyle intervention were a minimum of 7 percent weight loss through a low-fat, hypocaloric diet and a minimum of 150 minutes of exercise per week (such as brisk walking). Several behavioral components were used to help achieve these goals, including behavioral self-management training, individual case managers, group and/or individual sessions, individualized adherence strategies, and a network of training, feedback, and clinical support [29]. Using this approach, lifestyle intervention was more effective for preventing diabetes than a pharmacologic intervention (metformin); 58 versus 31 percent risk reduction at 3.1 years [6]. (See "Prevention of type 2 diabetes mellitus" and "Obesity in adults: Role of physical activity and exercise" and "Obesity in adults: Dietary therapy".)

Although a number of commercially available weight loss programs boast >10 percent weight loss, a meta-analysis of 22 behavioral weight loss studies showed just over 4 percent average loss compared with 1 percent for the control groups, with maximal effect within the first six months after the initiation of treatment [6,30,31]. Regrettably, as with other therapies for obesity, maintenance of these initial weight losses has been difficult [32].

Dietary therapy — Many types of diets produce modest weight loss. Options include balanced low-calorie, low-fat/low-calorie, moderate-fat/low-calorie, or low-carbohydrate diets, as well as the Mediterranean diet. Diets can be consumed conventionally or on a time-restricted basis (ie, intermittent fasting). Dietary adherence is an important predictor of weight loss, regardless of the type of diet chosen [33]. Thus, we advise tailoring a diet that reduces energy intake below energy expenditure to individual patient preferences, rather than focusing on the macronutrient composition of the diet. The addition of dietary counseling may facilitate weight loss, particularly during the first year. (See "Obesity in adults: Dietary therapy", section on 'Types of diets'.)

Metabolic studies using state-of-the-art techniques have concluded that most adults will lose weight when fed <1000 kcal/day. Thus, even subjects who are concerned that they are "metabolically resistant" to weight loss will lose weight if they comply with a diet of 800 to 1200 kcal/day. More severe caloric restriction might be expected to induce weight loss more quickly, but a comparison with 400 versus 800 kcal/day diet formulas showed no difference in weight loss [34], presumably due to slowing of resting metabolic rate. We thus advise diets consisting of >800 kcal/day. (See "Obesity in adults: Dietary therapy", section on 'Very low-calorie diets'.)

In addition, because of the body’s hormonal adaptation to perceived starvation, it is difficult to maintain a very low-calorie diet long-term. However, these diets may be used in certain conditions when rapid weight loss is needed (eg, to obtain metabolic control in uncontrolled type 2 diabetes mellitus or hypertension, or in preparation for a surgical procedure such as joint replacement, bariatric surgery, or organ transplantation).

Other dietary patterns, such as intermittent fasting (eg, alternate-day fasting or time-restricted feeding) are sometimes used to promote weight loss, although the evidence of their efficacy is mixed. (See "Obesity in adults: Dietary therapy", section on 'Intermittent fasting'.)

No matter which diet or dietary pattern is chosen, continued surveillance by both clinician and patient are essential for treatment success. Return visits with the clinician, dietician, or behaviorist should be scheduled at regular intervals to assess barriers, discuss next steps, and offer encouragement. If weight loss is less than 5 percent in the first six months, something else should be tried. (See "Obesity in adults: Behavioral therapy" and "Obesity in adults: Dietary therapy".)

Exercise — Although less potent than dietary restriction in promoting weight loss, increasing energy expenditure through physical activity is a strong predictor of weight loss maintenance. In addition, physical activity can attenuate the loss of lean mass (eg, muscle) during active weight loss [35]. Physical activity should be performed for approximately 30 minutes or more, five to seven days a week, to prevent weight gain and to improve cardiovascular health [36]. There appears to be a dose effect for physical activity and weight loss, and much greater amounts of exercise are necessary to produce significant weight loss in the absence of a calorically restricted diet. Therefore, when weight loss is the desired goal, a calorie-restricted diet should be combined with less sedentary time and increased physical activity; the activity should be gradually increased over time as tolerated. A multicomponent program that includes aerobic and resistance training is preferred. Existing medical conditions, age, and preferences for types of exercise should all be considered in the decisions. (See "Obesity in adults: Role of physical activity and exercise" and "Exercise prescription and guidance for adults", section on 'Prescribing an exercise program'.)

Behavior modification — Behavior modification or behavior therapy is one cornerstone in the treatment for obesity. The goal of behavioral therapy is to help patients make long-term changes in their eating behavior by modifying and monitoring their food intake, modifying their physical activity, and controlling cues and stimuli in the environment that trigger eating. These concepts are usually included in programs conducted by psychologists or other trained personnel as well as many self-help groups. (See "Obesity in adults: Behavioral therapy".)

Subsequent treatment — For patients who are unable to achieve weight loss goals with a comprehensive lifestyle intervention alone, options include pharmacologic therapy, the use of medical devices, or bariatric surgery. (See "Obesity in adults: Drug therapy" and "Bariatric surgery for management of obesity: Indications and preoperative preparation".)

Drug therapy — Drug therapy is often a helpful component in the treatment regimen for people with obesity; it can be considered for those with a BMI >30 kg/m², or a BMI of 27 to 29.9 kg/m² with weight-related comorbidities, who have not met weight loss goals (loss of at least 5 percent of total body weight at three to six months) with a comprehensive lifestyle intervention. The decision to initiate drug therapy should be individualized and made after a careful evaluation of the risks and benefits of all treatment options. (See "Obesity in adults: Drug therapy", section on 'Our approach'.)

The choice of anti-obesity drug depends upon patient comorbidities but also takes into account patient preferences, adverse effects, and insurance coverage and out-of-pocket costs. For most patients, a glucagon-like peptide 1 (GLP-1) agonist (eg, semaglutide. liraglutide) is the preferred first-line pharmacotherapy. Other options include combination phentermine-topiramate, orlistat, combination bupropion-naltrexone, and phentermine (as a single agent). The details of pharmacotherapy for the management of obesity are reviewed elsewhere. (See "Obesity in adults: Drug therapy", section on 'Sympathomimetic drugs' and "Obesity in adults: Drug therapy".)

Devices — There are several types of devices approved for use in the treatment of obesity. The use of one of these devices may be considered for use in those patients in whom medications are ineffective or not tolerated, for those patients who are unable or unwilling to undergo bariatric surgery, or as a bridging therapy prior to bariatric surgery. (See "Intragastric balloon therapy for weight loss", section on 'Indications'.)

In referring a patient to receive one of these devices, it is important to note that the BMI indication for each device is different, with a BMI range between 25 to 55 kg/m². In addition, the majority of insurance companies in the United States do not cover the costs of these devices; the financial burden to the patient may be significant depending upon which device is used. In addition to cost, recommendations for the use of any of these devices is dependent upon many other factors, including patient comorbidities, preferences, and weight loss goals.

●Intragastric balloon systems – With these techniques, saline filled balloons are placed in the stomach to take up space and produce a sensation of satiety (figure 3). They are indicated for weight reduction in conjunction with diet and exercise in adult patients with a BMI of 30 to 40 kg/m² and one or more obesity-related comorbid conditions, or for adult patients with obesity who have failed weight reduction with diet and exercise alone. There are five intragastric balloon systems available, three of which are approved by the United States (US) Food and Drug Administration (FDA). Of the three balloon systems available for use in the US, two of these devices are placed endoscopically while the other is swallowed; all three are removed endoscopically in 6 months. Intragastric balloon devices used for weight loss are discussed in detail elsewhere. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Intragastric balloon'.)

●Gastric emptying (aspiration) systems – A surgically placed gastrostomy tube is used to drain a portion of the stomach contents after every meal, decreasing the calories absorbed. These are intended to assist in weight loss in patients aged 22 and older with a BMI of 35 to 55 kg/m², and who have failed to achieve and maintain weight loss through nonsurgical weight-loss therapy. These devices are contraindicated in patients with eating disorders. Gastric emptying (aspiration) therapy is reviewed elsewhere. Of note, the gastric emptying aspiration system (AspireAssist) is no longer available in the United States. (See "Bariatric procedures for the management of severe obesity: Descriptions", section on 'Aspiration therapy'.)

●Hydrogels – Considered medical devices, hydrogels are orally administered products, taken twice daily before meals, which expand in the stomach and intestines to create a sensation of satiety. They are not systemically absorbed and are eliminated through the feces. Hydrogels are indicated for use as weight management aids for adults with a BMI of 25 to 40 kg/m² and are to be used in conjunction with diet and exercise. There is no restriction on how long the product can be used for weight management. In a randomized trial comparing patients taking 2.25 g twice daily of a cellulose and citric acid hydrogel product versus placebo for 24 weeks, those taking the hydrogel lost more weight (6.4 versus 4.4 percent) [37]. Prescribing information for cellulose and citric acid hydrogel is available in the drug monograph included within UpToDate.

●Bariatric endoscopy – Bariatric endoscopy includes the placement of gastric balloons as well as endoscopic sleeve gastroplasty (a procedure which uses a suturing device which creates a tubular shape similar to the sleeve gastrectomy). Further description of these techniques is beyond the scope of this document.

Bariatric surgery — Candidates for bariatric surgery include adults with a BMI ≥35 kg/m², or a BMI of 30 to 34.9 kg/m² with type 2 diabetes [38]. There is some evidence that the BMI criteria may differ among races. (See "Bariatric surgery for management of obesity: Indications and preoperative preparation".)

Several surgical approaches, collectively referred to as "bariatric surgery," have been used to treat obesity. All procedures, including investigational ones such as endoscopic sleeve gastroplasty, are reviewed separately. Bariatric surgical approaches can achieve as much as a 40 percent weight loss at 12 to 18 months post-procedure, with better long-term weight loss maintenance than nonsurgical approaches. (See "Bariatric procedures for the management of severe obesity: Descriptions".)

In addition to resulting in greater weight loss, bariatric surgery may also reduce obesity-related morbidity more than nonsurgical weight loss approaches. In the Swedish Obese Subjects (SOS) after 10 to 20 years of follow-up, patients receiving bariatric surgery (including gastric banding, vertical banded gastroplasty, gastric bypass) had greater reductions in obesity-related morbidity (diabetes, hypertension, dyslipidemia) and overall mortality than those in the conventionally treated group (hazard ratio [HR] 0.71, 95% CI 0.54-0.92) [16]. In a subsequent propensity score matched cohort study, 2161 patients with type 2 diabetes and severe obesity who underwent metabolic bariatric surgery were compared to 2161 similar nonsurgical patients treated with GLP-1 receptor agonists (81.7 percent liraglutide) [39]. During the study period, fewer surgical patients suffered major cardiovascular adverse events (MACE) or all-cause mortality than nonsurgical patients (8-year cumulative incidence 9.3 versus 11.3 percent, HR 0.76, 95% CI 0.59–0.98).

Further, in systematic reviews and meta-analyses of randomized trials comparing bariatric surgery to nonsurgical treatment of obesity (diet, exercise, weight-reducing drugs, behavioral therapy), there was greater weight loss and higher remission rates of type 2 diabetes in the bariatric surgery group [40,41]. Such results were further magnified when bariatric surgery was combined with intensive medical therapy [42]. The surgical management of obesity is reviewed in detail separately. (See "Bariatric surgery for management of obesity: Indications and preoperative preparation" and "Management of persistent hyperglycemia in type 2 diabetes mellitus", section on 'Bariatric (metabolic) surgery' and "Outcomes of bariatric surgery".)

THERAPIES THAT WE DO NOT RECOMMEND

Liposuction — We do not advocate liposuction as a strategy for long-term weight loss. Removal of fat by aspiration after injection of physiologic saline has been used to remove and contour subcutaneous fat. While this can result in a significant reduction in fat mass and weight, it does not appear to improve insulin sensitivity or risk factors for coronary heart disease. This was illustrated in a study of 15 obese women (eight with normal glucose tolerance and seven with type 2 diabetes) who underwent metabolic evaluation before and 10 to 12 weeks after large-volume abdominal liposuction with the following results [43]:

●Liposuction decreased the volume of subcutaneous abdominal adipose tissue by 44 percent (9 kg) in the women with normal glucose tolerance and by 28 percent (10.5 kg) in those with diabetes.

●Although waist circumference and plasma leptin concentrations were significantly decreased, no improvements in insulin sensitivity of muscle, liver, or adipose tissue were seen in either group.

●Liposuction did not alter plasma concentrations of C-reactive protein, interleukin-6, tumor necrosis factor-alpha, or adiponectin, and there were no significant improvements in other risk factors for coronary heart disease, including blood pressure, plasma glucose, lipid, or insulin concentrations. (See "Overview of established risk factors for cardiovascular disease".)

Thus, removal of large volumes of subcutaneous abdominal adipose tissue with liposuction does not improve insulin sensitivity or risk factors for coronary heart disease in women with obesity with or without type 2 diabetes, suggesting that the negative energy balance induced by decreased nutritional intake and/or removal of visceral fat are necessary for achieving the metabolic benefits of weight loss. (See "Obesity in adults: Dietary therapy".)

HCG — There is no evidence that treatment with human chorionic gonadotropin (HCG) is effective in the treatment of obesity [44]. Well-conducted trials have shown that it does not induce weight loss or fat redistribution, nor does it reduce hunger.

Dietary supplements — Although over-the-counter dietary supplements are widely used by individuals attempting to lose weight, we advise against their use because evidence to support their efficacy and safety are limited. Examples of dietary supplements include ephedra, green tea, chromium, chitosan, Vitamin B-12, and guar gum. Ephedra and ephedra alkaloids (Ma Huang), a group of ephedrine-like molecules found in plants, have been removed from the United States market because of safety concerns. (See "Obesity in adults: Drug therapy", section on 'Therapies not recommended' and "High-risk dietary supplements: Patient evaluation and counseling", section on 'Weight loss supplements'.)

Acupuncture — Acupuncture has also been studied for the treatment of obesity. While most studies have been uncontrolled trials, results from some, but not all, controlled trials have shown modest benefit of acupuncture for weight loss [45,46]. However, the majority of these controlled trials are small, of short duration, and do not include adequate placebo controls.

RISKS OF TREATMENT — Treatments for obesity can be divided according to the risk of side effects. For example, most of the available anti-obesity drugs have minor side effects that diminish with treatment; however, a few serious side effects have been identified that should preclude short-term use in people who wish to lose small amounts of weight (the majority of people) [47,48]. Chronic treatment may be needed when the magnitude of the obesity carries larger risks (eg, a BMI above 30 kg/m², or a BMI between 27 and 30 kg/m² with complicating factors such as diabetes mellitus or hypertension). (See "Obesity in adults: Drug therapy".)

Significant weight loss (achieved via any modality) may increase the likelihood of cholelithiasis because the flux of cholesterol through the biliary system increases. Diets with moderate amounts of fat that trigger gallbladder contraction may reduce this risk. Similarly, therapy with a bile acid (eg, ursodeoxycholic acid) may be advisable in selected subjects, such as those who are losing weight rapidly (>1 to 1.5 kg/week).

MAINTENANCE OF WEIGHT LOSS — Recidivism, the regaining of lost weight, is a common problem in treating people with obesity [49].

Characteristics of those who are likely to succeed in maintaining weight loss include frequent self-weighing, a larger initial weight loss (> 2 kg in four weeks), frequent and regular attendance at a weight loss program, a belief that their weight can be controlled, consumption of a reduced calorie (eg, 1400 kcal/day) low-fat diet, regular physical activity, and participation in a lifestyle intervention program [50,51]. (See "Obesity in adults: Behavioral therapy", section on 'Maintenance of weight loss' and "Obesity in adults: Dietary therapy", section on 'Role of dietary counseling' and "Obesity in adults: Role of physical activity and exercise", section on 'Exercise may help maintain weight loss'.)

The body appears to have a "set point" of adipose tissue mass, and after weight loss, counter-regulatory hormones are secreted to re-establish the higher body weight. In addition, the reduction in energy expenditure caused by weight loss itself contributes to the difficulty in maintaining weight loss [52-54]. (See "Obesity: Genetic contribution and pathophysiology", section on 'Resistance to weight loss and maintenance of reduced weight'.)

Lifestyle modification strategies that include diet and exercise remain the foundation of any long-term weight management plan. However, strategies that assume the effective treatment of obesity is only a matter of an individual's "willpower" may lead to repeated failure due to the body's tendency to revert to its set point [52]. Bariatric surgery, which may alter the body's adipose tissue set point, and extended use of anti-obesity pharmacologic therapy may help address these underlying physiologic changes. (See "Outcomes of bariatric surgery" and "Obesity in adults: Drug therapy".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Obesity in adults".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Weight loss treatments (The Basics)")

●Beyond the Basics topics (see "Patient education: Losing weight (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Benefits of weight loss - The medical rationale for weight loss is that obesity is a serious, chronic, and progressive disease and is associated with a significant increase in mortality (figure 1) and many health risks including type 2 diabetes mellitus, hypertension, dyslipidemia, and coronary heart disease. The benefits of weight loss include a reduction in the rate of progression from impaired glucose tolerance to diabetes, blood pressure in hypertensive patients, and lipid levels in higher risk patients. Other noncardiac benefits of weight loss include reductions in urinary incontinence, sleep apnea, and depression, as well as improvements in quality of life, physical functioning, and mobility. (See 'Importance of weight loss' above.)

●Identify candidates for treatment - Selection of treatment for people with overweight or obesity is based upon an initial risk assessment. (See 'Identify candidates' above.)

●Lifestyle modifications for all individuals - All patients who would benefit from weight loss should receive counseling on diet, exercise, and goals for weight management. (See 'Initial treatment' above.)

●Pharmacologic therapy - Candidates for pharmacologic therapy include adults with a body mass index (BMI) greater than 30 kg/m², or a BMI of 27 to 29.9 kg/m² with comorbidities, who have not met weight loss goals (loss of at least 5 percent of total body weight at three to six months) with a comprehensive lifestyle intervention. The decision to initiate drug therapy should be individualized and made after a careful evaluation of the risks and benefits of all treatment options (lifestyle, pharmacologic, surgical). Detailed recommendations for pharmacotherapy are discussed separately. (See 'Drug therapy' above and "Obesity in adults: Drug therapy".)

●Devices for weight loss - There are several types of devices approved for use in the treatment of obesity. The use of one of these devices may be considered for use in those patients in whom medications are ineffective or not tolerated, for those patients who are unable or unwilling to undergo bariatric surgery, or as a bridging therapy prior to bariatric surgery. In referring a patient to receive one of these devices, it is important to note that the BMI indication for each device is different, with a BMI range between 25 to 55 kg/m². (See 'Devices' above.)

●Bariatric surgery - Candidates for bariatric surgery include adults with a BMI ≥35 kg/m², or a BMI of 30 to 34.9 kg/m² with type 2 diabetes mellitus. (See 'Bariatric surgery' above.)

●Strategies to maintain weight loss - Consumption of a reduced calorie diet, frequent self-weighing, and participation in a lifestyle intervention program are strategies to help maintain weight loss. However, the body appears to have a "set point" of adipose tissue mass, and strategies that assume the effective treatment of obesity is only a matter of an individual's "willpower" may lead to repeated failure due to the body's tendency to revert to its set point. Bariatric surgery, which may alter the body's adipose tissue set point, and extended use of anti-obesity pharmacologic therapy may help address these underlying physiologic changes. (See 'Maintenance of weight loss' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges George Bray, MD, who contributed to an earlier version of this topic review.