We propose to conduct a randomized controlled efficacy trial (RT-1 set vs. RT-3 sets vs. non exercise control) to evaluate the potential for a longer intervention (9 months RT with body composition assessments 1 yr post RT completion) with a higher volume of RT (3 sets) to enhance the effects on body composition and energy expenditure observed in the pilot, and to determine the impact of the 2 levels of RT on free-living energy balance (expenditure by doubly labeled water and intake by digital photography and 24-hr recalls). This investigation will be conducted in a sample of healthy, normal and overweight, sedentary, young adult men and women; a group at high risk for development of overweight and obesity. The specific aims of this project are to determine the impact of the volume (1 vs. 3 sets) of a progressive RT protocol for inducing muscular hypertrophy, as recommended by the American College of Sports Medicine, on body weight and body composition (fat mass, fat-free mass (FFM), % body fat) and energy balance. Our results will provide information relative to the minimum volume of RT that may be associated with body weight/fat gain which may inform the development of guidelines for RT to prevent weight gain or to alter body composition. If RT has a favorable impact on energy balance and body composition, it may provide an attractive alternative to aerobic exercise for weight management for busy young adults, as RT requires minimal time, and no need to change clothes or shower (i.e. minimal or no sweating).