The effects of exercise on hunger and the hunger-related hormones ghrelin and peptide YY

Aerobic and resistance exercise have been promoted as a key component of exercise recommendations for weight control because exercise is an effective method of increasing energy expenditure and it may paradoxically, lead to a short-term hunger suppression. This phenomenon has been termed 'exercise induced anorexia' but the mechanisms are unclear so the relationship between exercise and hunger has led to a need for investigators to study the role of gut hormones in mediating exercise-induced hunger changes. The effect of acute exercise bouts on total plasma ghrelin concentrations is controversial and no studies have reported the effects of exercise on acylated ghrelin. There is also a paucity of data on the effects of exercise on total PYY. Several limitations are apparent in the research literature regarding exercise and gut hormones. Most studies have measured gut hormone responses for relatively short periods and few studies have assessed post-exercise gut hormone responses to feeding over a prolonged period or attempted to relate these responses to changes in hunger. Moreover, no studies have examined acylated ghrelin and PYY responses to resistance exercise. Therefore the purpose of the studies presented in this thesis is to investigate the acute effects of exercise on hunger and acylated ghrelin and the final study measured total PYY in healthy fasted participants to try and explain the mechanisms for 'exercise induced anorexia'. [Continues.]