Influence of intense physical activity on energy balance and body fatness

The reduced contribution of physical activity to daily energy expenditure and the accessibility to high-fat foods have put an excessive burden on energy balance, resulting in an increase in the prevalence of obesity throughout the world. In this context, fat gain can be seen as a natural adaptation to deal with a fattening lifestyle, since the hormonal adaptations that accompany fat gain favour the readjustment of energy expenditure to energy intake. Intense physical activity would also seem to facilitate the regulation of energy balance, since it increases the energy cost of exercise, increases post-exercise energy expenditure and the potential of skeletal muscles to utilize lipids, and also favours a decrease in post-exercise intake. Moreover, the effects of intense exercise seem to be mediated by an activation of sympathetic nervous system activity that seems to be specific to skeletal muscle. It is also important to manipulate macronutrient composition in order to reduce fat intake, because unhealthy food habits can favour overfeeding and thus overcome the energy deficit caused by regular physical activity. Under free-living conditions, the combination of vigorous activity and healthy food practices can amount to a substantial weight loss which is comparable with that of other non-surgical approaches to treat obesity.