Weight reduction can help reduce the complications of obesity. To achieve weight reduction, the obese patient must decrease energy intake or increase energy expenditure, although decreasing energy intake is thought to contribute more to inducing weight loss. Typically, a plan for weight reduction combines dietary change; increased physical activity; and behavioral modification, which can include nutrition education and meal planning, recording food intake through food diaries, modifying factors that lead to overeating, and relearning cues to satiety. Medications or surgery may be recommended. Once weight loss is achieved, weight maintenance is a separate process that requires vigilance because the majority of patients regain weight after they stop their weight-loss efforts.
B. Caloric restriction
Dieting is the most commonly practiced approach to weight control. Because 1 lb of adipose tissue corresponds to ~3,500 kcal, the effect that caloric restriction will have on the amount of adipose tissue can be estimated. Weight loss on calorie-restricted diets is determined primarily by caloric intake and not nutrient composition. [Note: However, compositional aspects can affect glycemic control and the blood lipid profile.] Caloric restriction is ineffective over the long term for many individuals. Over 90% of people who attempt to lose weight regain the lost weight when dietary intervention is suspended. Nonetheless, although few individuals will reach their ideal weight with treatment, weight losses of 10% of body weight over a 6-month period often reduce blood pressure and lipid levels and enhance control of T2D.
A. Physical activity
An increase in physical activity can create an energy deficit. Although adding exercise to a hypocaloric regimen may not produce a greater weight loss initially, exercise is a key component of programs directed at maintaining weight loss. In addition, physical activity increases cardiopulmonary fitness and reduces the risk of CVD, independent of weight loss. Persons who combine caloric restriction and exercise with behavioral treatment may expect to lose ~5%–10% of initial body weight over a period of 4–6 months. Studies show that individuals who maintain their exercise program regain less weight after their initial weight loss.
C. Pharmacologic treatment
The U.S. Food and Drug Administration has approved several weight-loss medications for use in adults. They include orlistat (decreases absorption of dietary fat), lorcaserin and phentermine in combination with topiramate (promote satiety through serotonin signaling), liraglutide (decreases appetite by activating the glucagon-like peptide 1 receptor), and buproprion in combination with naltrexone (increase metabolism by increasing norepinephrine). Their effects on weight reduction tend to be modest. [Note: Pharmacologic activation of brown adipocytes (see p. 79) is being explored.]
D. Surgical treatment
Gastric bypass and restriction surgeries are effective in causing weight loss in severely obese individuals. Through mechanisms that remain poorly understood, these operations greatly improve glycemic control in morbidly obese diabetic individuals. [Note: Implantation of a device that electrically stimulates the vagus nerve to decrease food intake has been approved.]
VIII. CHAPTER SUMMARY