Physical activity as a supplement to a weight-loss dietary regimen

Abstract

Many effects of exercise are potentially beneficial to weight boss and weight maintenance ( 1 ). A bout of exercise produces an increase in caloric expenditure, the magnitude of the increase being related to the duration, intensity, and type of exercise. Weight-bearing exercise leads to caloric expenditure that is directly related to body weight. Therefore, such activities as walking, jogging, and cross-country skiing would appear to have particular benefits for obese individuals. Muscle-strengthening exercises may produce an added advantage by maintaming or increasing muscle mass. Some have described a carry-over effect ofexercise on metabolic rate (2, 3) but this has been disputed (4). If any long-term effect exists, it probably occurs only after very vigorous and sustained physical activity. Exercise when combined with diet in the treatment of obesity would be expected to bead to greater body fat loss as well as better preservation of lean body mass (LBM) than diet alone. In addition, because resting energy expenditure (REE) is directly rebated to LBM (5), exercise added to a weight-boss regimen would be expected to prevent or lessen a diet-induced decrease in REE. Exercise may also favorably alter substrate and hormone levels associated with the complications of obesity (6), suppress appetite (7), alter substrate oxidation (8), and produce psychological effects of improved general well-being. The conventional wisdom regarding the beneficial aspects ofexercise in conjunction with diet has been chablenged. A recent study in women (9) indicated not only a lack of additional benefit of exercise in weight loss but also a reduction in REE when exercise was combined with diet compared with diet alone. However, a previous study from our laboratories ( 10) indicated clear benefits ofexercise in obese men. LBM was preserved and indices of physical fitness improved. To investigate whether a program of physical activity similar to that used in our previous approach with men would be beneficial in women, we carried out the following study ofthe effects ofexercise in a weight-loss dietary regimen.