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Obesity

About 35 percent of American adults (aged 20 years of age or older) are overweight. In addition, 14 percent of children between the ages of 6 and 11, and 12 percent of adolescents between the ages of 12 and 17 are overweight.

Pathophysiology. The adipocyte has endocrine capabilities and secretes leptin -- a protein product of the ob gene -- in response to increased stores of energy. Leptin limits food intake by acting upon the OB receptor in the hypothalamus. In many obese adults, leptin levels are increased, whereas leptin uptake.

Nutrition therapy

A meal plan that creates an energy deficit of 500 to 1,000 kcal per day less than the individual's average daily intake will usually be suitable for weight reduction. Along with caloric reduction, a reduction in total fat consumption should be recommended. Caloric restrictions for the treatment of overweight and obesity can be classified as follows:

Moderate deficit diet (all health risk groups). Women: 1200+ kcal per day; men: 1400+ kcal per day.

Low-calorie diet (moderate to extremely high health risk groups). Women: 800 to 1200 kcal per day; men: 800 to 1400+ kcal per day.

Very low-calorie diet (high to extremely high-health risk groups). Less than 800 kcal per day.

Among patients treated with a moderate deficit diet, weight losses average about 1 lb (0.45 kg) per week. Because even moderate deficit diets may pose nutritional concerns, such as deficiencies in calcium, iron, and folic acid, vitamin and mineral supplementation may be recommended.

Behavior modification methods

Stimulus control to detect and respond to environmental cues associated with unhealthy eating habits and physical inactivity (eg, refraining from eating when not hungry).

Self-supervision of eating habits and physical activity (eg, keeping a food and activity diary).

Positive reinforcement of beneficial lifestyle changes (eg, rewards; social support from family and friends).

Stress management (eg, relaxation techniques, meditation, problem-solving strategies).

Cognitive restructuring to moderate self-defeating thoughts and emotions (eg, redefining body image and modifying unrealistic goals).

Pharmacologic treatment

Pharmacotherapy should be considered only for individuals with high, very high, or extremely high BMI-based health risks:

Patients with a BMI of 30 kg per m² or more and no attendant risk factors.

Patients with a BMI of 27 kg per m² or more and one or more obesity-related comorbidities or other diseases.

Contraindications to pharmacotherapy include uncontrolled cardiovascular disease, pregnancy, lactation, history of psychiatric disease, and age below 18 years, and concomitant use of monoamine oxidase inhibitors (MAOIs).

Responders may exhibit preliminary weight losses of up to 1 lb (0.45 kg) per week; however, weight loss often plateaus or ceases after six to eight months of therapy. Most patients tend to regain weight after discontinuing pharmacotherapy, successful weight maintenance being contingent on significant improvements in dietary habits, physical activity, and behavior.

Phentermine (Fastin, Ionamin)

Most side effects of phentermine (eg, headache, nervousness, insomnia, irritability) are associated with central nervous system stimulation, but cardiovascular effects (eg, tachycardia), increased. 

Phentermine should not be used by patients with cardiovascular disease, glaucoma, hyperthyroidism, advanced arteriosclerosis, agitation.

Orlistat (Xenical) is an inhibitor of gastric and pancreatic lipase. Orlistat hinders the breakdown and absorption of dietary fats in the gastrointestinal system, resulting in body weight reduction and decreased serum cholesterol. Orlistat therapy produces greater weight loss.

The drug may significantly interfere with the uptake of the lipid-soluble vitamins A, E, and beta-carotene and/or antihypertensive agents, oral contraceptives, and lipid-lowering agents. Adverse effects of orlistat include abdominal pain, diarrhea, fecal incontinence, oily stools, nausea, vomiting.

Sibutramine ( Merida) is a reuptake inhibitor of both serotonin and norepinephrine. Sibutramine increases satiety after the onset of eating. Weight loss with sibutramine is dose-related. Sibutramine produces weight loss of 3 to 5 kg with 10 mg and 4 to 6 kg with 15 mg of sibutramine.

The most common side effects observed during treatment with sibutramine are headache, dry mouth, constipation, and insomnia. The most concerning side effect is hypertension. The mean increase in blood pressure is about 2 mm Hg systolic and diastolic at the 15-mg dose. At the 15-mg dose, approximately 13% of subjects experience an increase.

Sibutramine is available in 5-, 10-, and 15-mg doses given once per day. The recommended starting dose is 10 mg/d. The 15-mg dose can be used in subjects who do not respond adequately to 10 mg, and the 5-mg dose can be used.

Phenylpropanolamine ( Acutrim, Dexatrim) and a blend of Chinese herbs ( Dianixx) are the only over-the-counter products marketed as appetite suppressant medicines. Chromium salts and hydroxycitric acid have also been promoted as weight-loss agents. There is little scientific evidence to support the efficacy of any of these agents.

Surgical Therapy

Surgical therapy should be considered in patients with severe obesity meeting the following criteria:

A BMI of 40 kg per m² or more and have failed in attempts at medical treatment.

A BMI of 35 kg per m² or more with coexisting morbidities or other complicating risk factors.

The Roux-en-Y gastric bypass (RYGB) and vertical banded gastroplasty (VBG) are the two operative procedures most frequently employed for obesity. These techniques have been recommended because of safety and efficacy. In the RYGB procedure, the distal stomach is resected, and the remaining gastric pouch is anastomosed to a Roux-en-Y segment of the jejunum. In the VBG procedure, a prosthetic band (usually silicone or polypropylene plastic) is positioned on the stomach.