What are the clinical practice guidelines for managing and preventing obesity in adults with or without chronic diseases, including dietary recommendations, physical activity, pharmacological interventions, and surgical options?

Clinical Practice Guidelines for Managing and Preventing Obesity

Screening and Initial Assessment

All clinicians should screen all adult patients for obesity using BMI ≥30 kg/m² as the diagnostic threshold, and offer intensive counseling and behavioral interventions to promote sustained weight loss. 1

• Measure waist circumference to identify those at higher cardiometabolic risk, as central adiposity independently predicts adverse outcomes beyond BMI alone 1
• Screen for obesity-related comorbidities including type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, fatty liver disease, obstructive sleep apnea, and certain cancers 1, 2
• Assess social determinants of health and establish patient-centered goals that may include not only weight loss but also improvements in blood pressure, fasting glucose, or lipid levels 1, 3
• Use respectful, non-stigmatizing language and ask permission before discussing weight to establish a therapeutic relationship 3

First-Line Treatment: Comprehensive Lifestyle Intervention

Prescribe high-intensity comprehensive lifestyle programs consisting of at least 14 sessions over 6 months that combine dietary modification, physical activity, and behavioral strategies. 1, 3

Dietary Recommendations

• Create a 500-750 kcal/day deficit to achieve 0.25-1.0 kg weight loss per week 3
• Prescribe total daily intake of 1,200-1,500 kcal for women and 1,500-1,800 kcal for men 1, 3
• Ensure macronutrient balance: 55% carbohydrates, 10% protein, 30% fat (with ≤10% saturated fat) 4
• Very-low-calorie diets (<800 kcal/day) should only be used in limited circumstances under medical supervision with trained practitioners in medical care settings 1

Physical Activity Recommendations

• Prescribe ≥150 minutes per week of moderate-intensity aerobic activity initially for weight loss 1, 3
• Progress to 200-300 minutes per week for weight loss maintenance, as this amount is necessary to prevent weight regain 1, 5
• Include resistance training 2-3 times weekly to preserve lean muscle mass during weight loss 3, 6
• Walking is the most convenient and logical way for most obese persons to increase physical activity 6

Behavioral Strategies

• Provide regular self-monitoring of food intake, physical activity, and body weight (at least weekly) 1
• Deliver interventions through trained interventionists (registered dietitians, psychologists, exercise specialists, or health counselors) who adhere to formal weight management protocols 1
• Face-to-face sessions produce superior results, but electronically delivered programs with personalized feedback can be prescribed as an alternative, though they may result in smaller weight loss 1
• Some commercial programs with peer-reviewed published evidence of safety and efficacy can be prescribed as options 1

Expected Outcomes and Weight Loss Goals

Set an initial target of 5-10% body weight reduction over 6 months, as this produces clinically meaningful improvements in cardiovascular risk factors even without achieving ideal body weight. 1, 3

• Comprehensive lifestyle interventions produce on average 8 kg of weight loss (5-10% of initial body weight) 1
• Modest weight loss significantly improves glucose metabolism, lipid levels, blood pressure, and reduces progression to type 2 diabetes 1
• Weight loss of 5-8.5 kg is typically observed 6 months after intervention, with 3-6 kg maintained at 48 months 4

Second-Line Treatment: Pharmacotherapy

Offer pharmacologic therapy to patients with BMI ≥30 kg/m² OR BMI ≥27 kg/m² with weight-related comorbidities who have failed to achieve weight loss goals after 3-6 months of intensive lifestyle modification. 1, 3

FDA-Approved Long-Term Medications

• First-tier options: Tirzepatide, Semaglutide, and Liraglutide (GLP-1 receptor agonists with superior efficacy) 3, 7
• Alternative options: Phentermine-topiramate, Naltrexone-bupropion, and Orlistat 3, 7

Off-Label Medication Options

• Phentermine monotherapy: 15-37.5 mg daily, achieves approximately 6.0 kg weight loss at 28 weeks, with 46% achieving ≥5% weight loss 7, 8
• Diethylpropion: Produces 3.0 kg weight loss at 6 months 1, 7
• Bupropion monotherapy: Produces 2.8 kg weight loss at 6-12 months 1, 7
• Metformin: Associated with approximately 3% weight loss 7

Critical Prescribing Considerations

• Discuss side effects, lack of long-term safety data beyond 12 months (except orlistat), and the temporary nature of weight loss with medications before initiating therapy 1
• Weight loss attributable to medications is modest (<5 kg at 1 year), but this amount still produces clinically meaningful improvements in cardiovascular risk factors 1
• Phentermine should be avoided in patients with cardiovascular disease, uncontrolled hypertension, hyperthyroidism, or those taking monoamine oxidase inhibitors 7, 8
• For severe renal impairment (eGFR 15-29 mL/min/1.73 m²), maximum phentermine dose is 15 mg daily; avoid in end-stage renal disease 8
• Monitor blood pressure and heart rate periodically with sympathomimetic agents 7
• Avoid β-blockers (atenolol, metoprolol, nadolol, propranolol) as antihypertensives in patients with obesity, as they promote weight gain 7

Medication Efficacy Data

• Orlistat: 2.89 kg weight loss at 12 months 1
• Phentermine: 6.0 kg weight loss at 28 weeks 7
• The magnitude of increased weight loss is only a fraction of a pound per week compared to placebo 8

Third-Line Treatment: Bariatric Surgery

Refer patients with BMI ≥40 kg/m² OR BMI ≥35 kg/m² with obesity-related comorbidities who have not achieved sufficient weight loss with behavioral treatment ± pharmacotherapy for bariatric surgery consultation. 1, 3

Surgical Candidacy Criteria

• Patients must be motivated to lose weight and have not responded to behavioral treatment with or without pharmacotherapy 1
• Refer to an experienced bariatric surgeon at a high-volume center for consultation and evaluation 1, 7
• For patients with BMI <35 kg/m², there is insufficient evidence to recommend for or against bariatric procedures 1

Surgical Options

• Laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass are the primary surgical options 3
• Choice of procedure depends on patient factors (age, BMI severity, comorbidities, operative risk), behavioral/psychosocial factors, patient risk tolerance, and provider factors 1

Weight Loss Maintenance Strategy

Prescribe long-term (≥1 year) comprehensive weight loss maintenance programs with at least monthly contact with a trained interventionist. 1, 3

• Maintain high levels of physical activity (200-300 minutes/week) 1, 3
• Continue weekly self-weighing or more frequently 1
• Maintain reduced-calorie diet needed to sustain lower body weight 1
• Continue long-term pharmacotherapy when lifestyle interventions alone are inadequate 3
• Face-to-face or telephone-delivered maintenance programs with regular contact help participants sustain weight loss 1

Prevention of Obesity

Promote achievement of at least 150 minutes per week of moderate-to-vigorous physical activity among all adults to prevent weight gain and obesity development. 1, 5

• At least 60 minutes of moderate-intensity physical activity daily may be necessary to prevent weight gain and obesity development 5
• For individuals unable to achieve minimum recommendations, encourage at least some moderate-to-vigorous physical activity, as this is still beneficial for reducing cardiovascular risk 1
• Physical activity confers health benefits even in the absence of weight loss and may counteract negative influences of body weight on health outcomes 5, 6

Common Pitfalls to Avoid

• Do not delay effective treatment by trialing unproven supplements when evidence-based medications are available 7
• Do not prescribe phentermine within 14 days of monoamine oxidase inhibitors due to hypertensive crisis risk 7
• Do not use nutritional supplements, herbs, or botanicals for obesity management, as there is no clear evidence of efficacy 7
• Do not prescribe very-low-calorie diets outside of medical supervision in specialized settings 1
• Do not underestimate the importance of long-term maintenance programs, as weight regain is common without continued support 1, 3