Weight reduction can be beneficial in reducing the complications associated with obesity. In order to achieve weight reduction, obese individuals can either decrease their energy intake or increase their energy expenditure. However, it is believed that decreasing energy intake contributes more to inducing weight loss. A typical weight reduction plan combines dietary changes, increased physical activity, and behavioral modification. Behavioral modification can involve nutrition education, meal planning, recording food intake through food diaries, modifying factors that lead to overeating, and relearning cues to satiety. Medications or surgery may also be recommended. It is important to note that once weight loss is achieved, weight maintenance requires vigilance as most patients tend to regain weight after they stop their weight-loss efforts.

Caloric restriction is the most commonly practiced approach to weight control. It is estimated that reducing caloric intake can lead to a decrease in adipose tissue, as 1 lb of adipose tissue corresponds to approximately 3,500 kcal. The effectiveness of caloric restriction over the long term is limited for many individuals, as over 90% of people who attempt to lose weight regain the lost weight when dietary intervention is suspended. However, weight losses of around 10% of body weight over a 6-month period often result in reduced blood pressure and lipid levels, as well as improved control of type 2 diabetes (T2D). It is important to note that the impact of caloric restriction on glycemic control and blood lipid profile can be influenced by nutrient composition.

Increasing physical activity can create an energy deficit and is an important component of programs aimed at maintaining weight loss. While adding exercise to a hypocaloric regimen may not initially lead to greater weight loss, it plays a key role in sustaining weight loss. Physical activity also improves cardiopulmonary fitness and reduces the risk of cardiovascular disease, independent of weight loss. Combining caloric restriction, exercise, and behavioral treatment can result in a weight loss of approximately 5% to 10% of initial body weight over a period of 4 to 6 months. Studies have shown that individuals who maintain their exercise program tend to regain less weight after their initial weight loss.

The U.S. Food and Drug Administration has approved several weight-loss medications for use in adults. These include orlistat (which decreases the absorption of dietary fat), lorcaserin and phentermine in combination with topiramate (which promote satiety through serotonin signaling), liraglutide (which decreases appetite by activating the glucagon-like peptide 1 receptor), and buproprion in combination with naltrexone (which increases metabolism by increasing norepinephrine). However, the effects of these medications on weight reduction are generally modest. Researchers are also exploring the activation of brown adipocytes through pharmacologic means.

For severely obese individuals, gastric bypass and restriction surgeries are effective in causing weight loss. The mechanisms by which these operations greatly improve glycemic control in morbidly obese diabetic individuals are not well understood. Additionally, the implantation of a device that electrically stimulates the vagus nerve to decrease food intake has been approved.

In summary, weight reduction through various approaches, including caloric restriction, physical activity, pharmacologic treatment, and surgical treatment, can have significant benefits for obese individuals. However, it is important to note that long-term weight maintenance requires ongoing efforts and vigilance.
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