Treatment: Obesity

Obesity is a chronic medical condition that requires ongoing treatment and lifestyle modifications. Treatment is important because of the associated health risks, but is made difficult by a limited repertoire of effective therapeutic options. Weight regain after weight loss is common with all forms of therapy. The urgency and selection of treatment modalities should be based on BMI and a risk assessment.

Diet, exercise, and behavior therapy are recommended for all pts with a BMI ≥25 kg/m². Behavior modification including group counseling, diet diaries, and changes in eating patterns should be initiated. Food-related behaviors should be monitored carefully (avoid cafeteria-style settings, eat small and frequent meals, eat breakfast). A deficit of 7500 kcal will produce a weight loss of approximately 1 kg. Therefore, eating 100 kcal/d less for a year should cause a 5-kg weight loss, and a deficit of 1000 kcal/d should cause a loss of ~1 kg per week. Physical activity should be increased to a minimum of 150 min of moderate intensity physical activity per week.

Pharmacotherapy may be added to a lifestyle program for pts with a BMI ≥30 kg/m² or ≥27 kg/m² with concomitant obesity-related diseases. Orlistat (120 mg po tid), an inhibitor of intestinal lipase, causes modest weight loss (9-10% at 12 months with lifestyle measures) due to drug-induced fat malabsorption. Lorcaserin and phentermine/topiramate are anorexiants that were recently FDA-approved. Response to medications should be assessed after 3 months. Metformin, exenatide, and liraglutide tend to decrease body weight in pts with obesity and type 2 diabetes mellitus, but they are not indicated for pts without diabetes.

Bariatric surgery should be considered for pts with severe obesity (BMI ≥40 kg/m²) or moderate obesity (BMI ≥35 kg/m²) associated with a serious medical condition, with repeated failures of other therapeutic approaches, at eligible weight for >3 years, capable of tolerating surgery, and without addictions or major psychopathology. Weight-loss surgeries are either restrictive (limiting the amount of food the stomach can hold and slowing gastric emptying), such as laparoscopic adjustable silicone gastric banding, or restrictive-malabsorptive, such as Roux-en-Y gastric bypass (Fig. 172-1). These procedures generally produce a 30-35% weight loss that is maintained in about 40% of pts at 4 years. In many patients, there is significant improvement in co-morbid conditions including type 2 diabetes mellitus, hypertension, sleep apnea, hyperlipidemia, and cardiovascular events. The metabolic benefits appear to be the combined result of weight loss and physiologic responses of gut hormones and adipose tissue metabolism. Complications include stomal stenosis, marginal ulcers, and dumping syndrome. Procedures with a malabsorptive component require lifelong supplementation of micronutrients (iron, folate, calcium, vitamins B₁₂ and D) and are associated with a risk of islet cell hyperplasia and hypoglycemia.

For a more detailed discussion, see Flier JS, Maratos-Flier E: Biology of Obesity, Chap. 415e, and Kushner RF: Evaluation and Management of Obesity, Chap. 416, p. 2392, in HPIM-19.