E-MECHANIC Ancillary Study: Effect of Exercise-Induced Weight Loss on Energy Metabolism

This is an ancillary study to E-Mechanic, which is an National Institutes of Health study in 198 individuals with the objective to understand why certain people fail to lose weight in exercise programs. In E-Mechanic changes in body weight, body composition, energy intake and energy expenditure are measured before and after 3 different exercise programs of 24 weeks in duration. The 3 exercise programs being compared are self-directed exercise, low dose exercise and high dose exercise. The goal of this ancillary study is to undertake comprehensive assessments of energy metabolism in a metabolic chamber in a group of 60 obese individuals enrolled in the main study. We will compare differences in the changes in 24h energy expenditure and spontaneous physical activity between the 3 exercise programs. We will also test if changes in energy metabolism might explain why people don't lose the expected amount of weight after 24 weeks of exercise.