Metabolic effects of overnutrition during physical inactivity

Physical inactivity is a significant predictor of major non-communicable diseases such as type 2 diabetes, cardiovascular disease, musculoskeletal disorders and some cancers, and has been proposed to be the 4th leading cause of death worldwide. Reduced physical activity leads to an impaired metabolic response of skeletal muscle to insulin and nutrition (insulin and anabolic resistance), as well as a loss of skeletal muscle mass and function. Physical inactivity also leads to the accumulation of various lipid species within muscle cells. These metabolic perturbations are also observed with over feeding i.e. both scenarios create a positive energy balance. The purpose of the present proposal is to elucidate the contribution of overfeeding to the negative effects of physical inactivity. The project will involve a series of in vivo metabolic physiology studies to assess insulin sensitivity, nutrient sensitivity, and physical function in healthy young human participants before and after dramatically reducing their habitual physical activity levels during under and over feeding.