What is the recommended evaluation and management plan for an adult with obesity (BMI ≥ 30 kg/m²), including assessment of comorbidities, lifestyle intervention, pharmacotherapy options, and criteria for bariatric surgery?

Evidence-Based Management of Adult Obesity (BMI ≥ 30 kg/m²)

All adults with obesity should receive comprehensive lifestyle intervention as first-line therapy, with pharmacotherapy added when weight-loss goals are not met after 6 months, and bariatric surgery considered for BMI ≥ 35 kg/m² with comorbidities or BMI ≥ 40 kg/m² when non-surgical measures fail. 1

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Initial Assessment and Risk Stratification

Anthropometric Measurements

• Measure BMI at every visit to confirm obesity (BMI ≥ 30 kg/m²). 1
• Obtain waist circumference in all patients: elevated risk is defined as ≥35 inches in women and ≥40 inches in men. 1
• In patients with BMI < 35 kg/m², waist circumference is essential because it detects central adiposity that independently predicts cardiometabolic and cardiovascular disease risk beyond BMI alone. 1

Comorbidity Screening

Systematically evaluate for the following obesity-related complications:

• Type 2 diabetes: fasting glucose ≥126 mg/dL or HbA1c ≥6.5%. 1
• Prediabetes: fasting glucose 100–125 mg/dL or HbA1c 5.7–6.4%. 1
• Hypertension: blood pressure ≥130/80 mmHg. 1
• Dyslipidemia: obtain fasting lipid panel. 1
• Obstructive sleep apnea: use STOP-BANG screening questionnaire. 1
• Non-alcoholic fatty liver disease: check liver function tests and calculate Fibrosis-4 Index. 1
• Cardiovascular disease: assess for coronary heart disease, peripheral arterial disease, and carotid artery disease. 1
• Osteoarthritis: evaluate weight-bearing joints for pain and functional limitation. 1
• Metabolic syndrome: document presence based on standard criteria. 1

Cardiovascular Risk Factors

• Document cigarette smoking, family history of premature coronary disease, age (men ≥45 years, women ≥55 years or postmenopausal), and physical inactivity. 1

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Lifestyle Intervention (First-Line Therapy for All Patients)

Dietary Therapy

• Prescribe a daily energy deficit of 500–1,000 kcal to achieve 1–2 lb (0.5–1 kg) weight loss per week, targeting 10% body-weight reduction at 6 months. 1
• Reducing dietary fat alone is insufficient; combine fat reduction with carbohydrate reduction to achieve the necessary caloric deficit. 1
• Use structured meal plans, portion control, and meal replacements to improve adherence. 2
• Avoid nutritionally unbalanced "fad" diets, which lack evidence of safety or efficacy. 2
• Reserve very-low-calorie diets (≤800 kcal/day) for specific indications (e.g., rapid weight loss needed for severe complications) and provide medical supervision. 2, 1

Physical Activity Prescription

• Prescribe ≥150 minutes/week of moderate-intensity aerobic activity (50–70% of maximal heart rate), distributed over at least 3 days with no more than 2 consecutive rest days. 1
• Add resistance training ≥2 times/week to improve lean-mass preservation and metabolic health. 1
• Emphasize activities of daily living (walking, cycling, gardening) that match the patient's capabilities and preferences. 2
• For patients with BMI > 35 kg/m², select low-impact exercises (e.g., swimming, cycling) to minimize musculoskeletal stress. 2, 1
• Counsel patients to reduce sedentary behaviors such as prolonged TV watching or computer use. 2

Behavioral Therapy

• Provide high-intensity behavioral counseling with ≥14 sessions within 6 months (individual or group) by trained interventionists. 1
• Address stress, unhealthy sleep habits, social dynamics, and environmental factors that promote obesity as part of behavioral modification. 2

Expected Outcomes

• Comprehensive lifestyle treatment yields an average weight loss of 8% of initial body weight (≈8 kg) over 6 months. 1

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Pharmacologic Therapy (When Lifestyle Modification Fails)

Initiation Criteria

• Offer anti-obesity medication to patients with BMI ≥30 kg/m², or BMI ≥27 kg/m² with obesity-related comorbidities (e.g., type 2 diabetes, hypertension, dyslipidemia, obstructive sleep apnea). 2, 1
• Pharmacotherapy must be combined with ongoing lifestyle modification and behavioral therapy—it is not appropriate as monotherapy. 2, 1
• Before prescribing, discuss potential side effects, limited long-term safety data beyond 12 months (except for orlistat), and the typically temporary nature of medication-induced weight loss. 2

Continuation Criteria

• Continue medication only if the patient loses ≥5% of initial body weight within the first 3 months OR ≥2 kg within the first 4 weeks of therapy. 2, 1
• Discontinue the medication if these weight-loss thresholds are not met. 2, 1

Expected Efficacy

• GLP-1 receptor agonists produce approximately 8–15% weight loss. 1
• Dual GLP-1/GIP receptor agonists achieve roughly 15–21% weight loss. 1
• Older agents (orlistat, sibutramine) produce modest weight loss (<5 kg) after one year. 2, 1

Adverse-Effect Monitoring

• Orlistat: monitor for fecal urgency, oily spotting, flatulence, and fat-soluble vitamin deficiency. 1, 3
• Sibutramine: monitor for increases in blood pressure and heart rate. 1, 3

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Bariatric Surgery (When Non-Surgical Interventions Fail)

Indications

• Consider surgery for BMI ≥40 kg/m² regardless of comorbidities. 2, 1
• Consider surgery for BMI ≥35 kg/m² with severe obesity-related complications (type 2 diabetes, hypertension, obstructive sleep apnea, severe joint disease, metabolic syndrome). 2, 1
• Surgery is indicated when comprehensive non-surgical interventions (lifestyle, behavioral, pharmacologic) have failed. 2, 1
• For patients with BMI > 40 kg/m² who have not achieved sufficient weight loss with anti-obesity medication, promptly refer for bariatric surgery as the definitive treatment. 4

Special Populations

• Bariatric surgery may be offered to patients with type 2 diabetes and BMI 30–34.9 kg/m², although evidence is limited and long-term data are lacking. 1

Expected Outcomes

• Bariatric procedures result in an average weight loss of 25–30% of initial body weight. 1
• Post-operative mortality is low (≈0.2%); complications include wound infection, re-operation (up to 25% of patients), vitamin deficiencies, diarrhea, and hemorrhage. 1

Pre-operative and Post-operative Care

• Require multidisciplinary pre-operative assessment (surgical risk, psychological readiness, commitment to lifelong lifestyle change). 2, 1
• Provide lifelong lifestyle support, nutritional supplementation, monitoring for complications, and ongoing behavioral counseling after surgery. 2, 1
• Counsel patients regarding short- and long-term risks, benefits, and outcomes of surgery and the lifelong commitment required to prevent weight regain. 2
• Monitor for nutrient deficiency and obesity-related complications post-operatively. 2

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Long-Term Weight Maintenance

• Schedule regular follow-up visits to provide accountability, monitor progress, and adjust treatment plans based on weight change, side effects, and achievement of metabolic targets. 1
• Enroll all patients who achieve weight loss in a comprehensive maintenance program lasting ≥1 year, with regular (monthly or more frequent) contact with a trained interventionist. 1
• Maintenance goals include 200–300 minutes/week of physical activity, weekly weight monitoring, and a modest calorie-restricted diet to sustain the lower weight. 1
• Counsel patients that weight regain is common after weight loss, including after bariatric surgery. 2
• Consider all options for supportive care, including pharmacotherapy, to help maintain weight close to the post-surgical nadir. 2

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Clinical Pitfalls to Avoid

• Do not rely solely on BMI for risk assessment—always measure waist circumference because central adiposity independently predicts cardiovascular risk. 1
• Do not use anti-obesity medication as monotherapy—it must be paired with lifestyle and behavioral interventions. 2, 1
• Discontinue pharmacotherapy if the patient fails to achieve ≥5% weight loss within 3 months or <2 kg loss within 4 weeks. 2, 1
• Do not delay bariatric surgery referral in patients with BMI ≥40 kg/m² who have failed pharmacotherapy—surgery is the definitive treatment for severe obesity. 4