Impact of experimental manipulation of energy intake and expenditure on body composition

There is persuasive evidence that much obesity is due to underexercising rather than overeating. In a series of randomized, controlled trials we found that sedentary men who take up jogging lose body fat in proportion to miles run, increase their energy intake, and improve their lipoprotein pattern. In a 1-year comparison of fat loss by dieting vs. fat loss by exercise without dieting, both methods were found to be effective in moderately overweight men, and both approaches raised plasma HDL cholesterol. We also demonstrated in overweight men and women losing weight on a prudent diet (low fat, low cholesterol) that adding exercise to energy restriction further increased loss of body fat and reduced waist-to-hip girth ratio, especially in men. Risk of coronary heart disease was also substantially further reduced by addition of exercise, in both sexes. These studies suggest that regular exercise is a valuable addition to dietary change for weight control and reduction of risk of chronic disease in people of all ages. In this article I shall describe studies done by our group in the past 10 years to investigate the effects of varying energy expenditures and varying caloric intakes on body composition, in particular body fat content. The intervention studies are of relatively long duration (1 or 2 years) and have been conducted in free-living men and women. Such long-term investigations are rare in children and adolescents. Although experience in adults cannot be translated directly to children, our findings may indicate profitable research directions for future obesity research in the young.(ABSTRACT TRUNCATED AT 250 WORDS)