Exercise and the neurobiological control of food intake and energy expenditure

Knowledge of the effects of exercise in the regulation of energy balance is imperative for the assessment of the value (or limit) of exercise as a therapeutic adjunct in the treatment of obesity. This short review addresses the effects of exercise on the neurobiological control of food intake and energy expenditure. It has been proposed that exercise may affect the regulation of energy balance through the stimulation of corticotropin-releasing hormone (CRH) and neuropeptide Y (NPY). It is likely that the CRH and NPY neuropeptidergic systems exert some degree of control on food intake and energy expenditure. The increase in the CRHergic activity induced by moderately intense exercise would potentiate the effects of muscular activity in reducing energy stores by decreasing energy intake and increasing thermogenesis. Reduced food intake and increased thermogenesis are two of the more recognized biological actions of CRH. Exercise would also contribute to the stimulation of brain NPY neurons by reducing energy stores and plasma insulin levels. By producing orexigenic effects and reducing thermogenesis, activation of the NPY system would tend to oppose the physiological effects of CRH and therefore cancel out the effects of exercise on energy loss.