Long-term Exercise, Weight Loss and Energy Balance

In order to examine potential gender differences in the weight loss response to exercise, the investigators propose to compare equal energy expenditure of exercise for overweight men and women using levels of exercise energy expenditure that the investigators have previously shown to prevent weight gain or promote weight loss. The investigators will randomize men and women to an exercise group, 5 days/week, for 9 months, with an energy expenditure of 400 kcal/exercise session, a group with 600 kcal/ exercise session, or a control group. 1)The investigators 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) The investigators 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) The investigators 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. The investigators believe the findings from this study could have important implications for exercise guidelines for weight loss.