Obesity is a major health problem in Western countries, affecting nearly 30% of adults. Obesity increases the risk of a variety of diseases, including heart disease and stroke. Total weight and fat deposition patterns are related to increased mortality. People who store fat in the abdomen are at greater risk than those who store it in the lower body.
Energy balance determines whether body fat increases, decreases, or remains the same, The cause of the positive energy balance in obese people is not totally understood although the answer probably lies in the complex physiological and psychological factors that control food intake and energy expenditure. The control center for food intake is located in the hypothalamus. The hunger center max, be regulated by glucose, stored triglycerides, plasma amino acid levels, and hypothalamic temperature.
The components of energy expenditure include resting metabolic rate（RMR）, thermogenesis, and physical activity. RMR usually decreases during weight loss. Exercise increases metabolic rate and spares lean body weight during weight loss. Thermogenesis is stimulated by eating and processing meals. In some species, brown fat may be an important center of thermogenesis although its importance in adult humans is not known. Exercise contributes to weight loss and is important for maintaining weight loss.
Fat cells increase in size and number during growth. In adults, most increases in body fat occur due to fat cell hypertrophy. Recent evidence suggests that fat cells can be gained or lost in adults.
Common treatments for obesity include diet, exercise, drugs, surgery, liposuction, and hypnosis. Most weight - control programs are not successful. Successful weight - loss programs require caloric restriction and basic changes in lifestyle (behavior modification). Exercise enhances the chances of successful long - term weight loss.
The three most important considerations determining the ideal body composition are health, aesthetics, and performance. Exercise helps each of these by preserving lean body mass and decreasing fat mass.
