Nutrition, Exercise and Muscle Metabolism in Obesity

Obesity is a major public health issue and its association with insulin resistance greatly increases risks for cardiovascular disease and type 2 diabetes. Exercise training is recommended for obese populations, but longitudinal studies indicate aerobic exercise training in obese individuals in the absence of weight loss has minimal impact on insulin resistance. High turnover of fat stored within muscle cells (i.e., intramyocellular triglyceride) during exercise and elevated muscle fitness (i.e., muscle oxidative capacity) are key features of the enhanced insulin sensitivity observed in endurance-trained individuals. It could be that longitudinal studies of exercise training in obese individuals failed to sufficiently stimulate intramyocellular triglyceride turnover during exercise and muscle oxidative adaptation as a result of failure to consider the impact of recent nutrition within their study designs. Performing exercise in the fed vs. fasted state can blunt these exercise responses in non-obese individuals. The researchers will investigate the hypothesis that an acute bout of aerobic exercise performed in the overnight-fasted versus fed-state can stimulate greater intramyocellular triglyceride utilization during exercise and enhanced expression of genes related to muscle oxidative adaptation in obese individuals. The expected outcomes will help to determine if exercising in the fasted state could be used to optimise metabolic adaptation to training in obese individuals. The future impact of this research could be the recommendation of a simple nutritional strategy considering meal timing to enhance the effects of aerobic exercise training in obese individuals, with potential long-term benefits for reducing insulin resistance and cardio-metabolic disease risk.