We request renewal of DK 49181 "Long-term exercise, weight loss, and energy balance." We propose to continue our investigation on exercise alone for weight loss in men and women. The results from DK49181 clearly indicted a gender difference in response to exercise with men losing weight (-2.9kg, ~6%) and women maintaining weight (+0.6kg). However, the energy expenditure of exercise was greater for men than women by about 240 kcal energy expenditure of exercise/session;therefore, it was not possible to determine if the apparent gender difference was due to the difference in the energy expenditure of exercise or truly attributed to a difference in response to exercise between men and women. In order to examine potential gender differences in the weight loss response to exercise, we propose to compare equal energy expenditure of exercise for overweight men and women using levels of exercise energy expenditure that we have previously shown to prevent weight gain or promote weight loss. We will randomize men and women to an exercise group, 5 days/week, for 10 months, with an energy expenditure of 400 kcal/exercise session, a group with 600 kcal/ exercise session, or a control group. 1) We hypothesize that men and women randomized to sedentary control will gain weight, those randomized to 400 kcal/exercise session will maintain weight (will not gain), and those randomized to 600 kcal/exercise session will lose ~5% of body weight. 2) We hypothesize there will be no differences for weight loss between genders at either 400 or 600 kcal of energy expenditure of exercise since men and women will have equal amounts of energy expenditure of exercise. 3) We hypothesize that men and women randomized to 400 kcal/exercise session will completely compensate for the energy expended during exercise by altering energy intake and/or spontaneous activity and that men and women participants randomized to 600 kcal/exercise session will not completely compensate. We believe the findings from this study could have important implications for exercise guidelines for weight loss.