The role of exercise in the treatment of obesity

The prevalence of obesity in the USA has increased dramatically in the past decade. This foreshadows an increase in the rates of morbidity and mortali ty from obesity-related diseases and increases in the number of individuals undergoing weight-loss therapy. Although exercise has long been recommende d for inclusion in such therapy, the present review has found that it has h ad little or no effect on weight loss per se when the exercise is limited t o the typically prescribed 3-5 h/wk of moderate or vigorous activity. Howev er, further review has shown that exercise helps to-preserve and at times e ven increase fat-free mass during weight loss. At the same time, fat loss i s generally increased. Neither type nor amount of exercise appears to have much effect during treatment, with the: possible exception of resistance tr aining, which is associated with the best outcome for fat-free mass. The mo st important role of exercise, however, is in the maintenance of the weight loss. In this respect,. the volume of exercise seems to be important becau se several lines of evidence have indicated that exercise must expend rough ly 2500 kcal/wk to maintain weight loss. Studies of weight maintenance, how ever, have generally not included randomized controls; thus, further resear ch is required to solidify these conclusions. (C) Elsevier Science inc. 200 0.