What processes are involved in the appetite response to moderate increases in exercise-induced energy expenditure?

Abstract

It is intuitive that an energy deficit induced by exercise induces an automatic increased drive for food (hunger and energy intake). However, the absence of a compensatory increase in energy intake (EI) in response to an exercise-induced increase in energy expenditure (EE) is now well documented. Thus, there is a weak coupling between exercise-induced increases in EE and EI. One paradox related to the phenomenon of a weak coupling between the exercise-induced EE and EI is the observation of a positive relationship between physical activity and food intake in the long-term free-living situation (i.e. tight coupling between EE and EI). It is possible, therefore, that a period of transition (uncoupling) occurs in the short-term, before a steady-state (coupling) condition is achieved. It is likely that a combination of physiological and behavioural adaptations occur in order to achieve a tight coupling between EE and EI. The precise physiological and behavioural changes that take place to obtain a new equilibrium (i.e. coupling between EE and EI) are still undetermined. The expectation that exercise-induced increases in EE should drive up hunger and food intake tends to be based on the concept of a strong coupling between physiology and behaviour. However, because of the individual's strong volitional control over eating behaviour, the psychological influences on the appetite response to exercise should not be undervalued. The psychological position of the individual (e.g. dietary restraint, food-related cognitions, reasons for exercising) could have a very strong influence on the food intake response to exercise. Misjudgements concerning the energy value of the food (EI) relative to the energy value of the exercise (EE) could be one possibility why exercise fails to be a successful method of weight loss for some individuals.