Exercise and metabolism. Dietary restriction decreases metabolism, and weight loss reduces the number of calories expended during physical activity. But patients who exercise vigorously are more likely to keep off all or most of the weight they lose. This is why doctors recommend exercise as a mainstay of weight loss and weight maintenance programs. Strength training prevents the loss or increases muscle mass while dieting, and both resistance and aerobic activity increase resting metabolic expenditure .
Exercise also helps improve insulin sensitivity, cardiovascular function and lipids.
The American College of Sports Medicine recommends an energy expenditure of at least 300 calories a day . Exercise can also improve metabolism in patients on VLC diets. In a 1995 study comparing activity level and weight maintenance among patients on a VLC diet, researchers found that patients with a high level of activity regained substantially less weight than less active patients. Dietary fat and metabolism. Rodent studies have consistently shown that diets high in fat-derived energy result in obesity, increased body fat content and hyperphagia .