Participants will undergo nutritional counseling and have supervised exercise training 4 days per week until 7-10% weight loss is achieved. Meals will be provided and food diaries will be kept during weight loss. Tests before and after the intervention will include muscular strength and aerobic fitness, cardiovascular assessments, glucose tolerance tests, hyperinsulinemic euglycemic clamp test for insulin sensitivity, heavy water metabolism, resting energy expenditure/metabolic rate, muscle and fat biopsies, body composition scans, blood tests, and urine and stool collection.