A sedentary lifestyle results in numerous physiologic and functional declines that increase risk for disease. Obesity and weight gain in sedentary adults are strongly associated with the development of hypertension, hyperlipidemia, and insulin resistance, which are risk factors for cardiovascular disease (CVD). Adults should sustain physical activity to perhaps prevent the age-associated increases in weight gain and fat mass. Aerobic exercise training provides numerous health benefits to adults, including increases in physical fitness and well-being, reductions in blood pressure, improvements in lipoprotein lipid profiles and glucose metabolism, and increases in bone mineral density. The focus of this chapter is to provide a review of the studies that have examined the effects of aerobic or endurance exercise training on adiposity, specifically total body fat, in order to better understand if beneficial body composition changes result from aerobic exercise training.