Investigation of the role of exercise and restrained eating behaviour on appetite control.

Obesity is a global epidemic; physical inactivity and increased consumption of highly palatable energy-dense food are likely to be the main drivers. However, little is known about the impact of exercise and dietary restraint on appetite control. The role of a six-week moderate intensity exercise intervention on short-term appetite regulation was investigated. Energy intake at a buffet test-meal was measured 60 minutes following two covertly manipulated preloads (607 and 246kcal) in healthy sedentary normal-weight volunteers at baseline and after the exercise intervention. Exercise was shown to improve short-term appetite control, leading to a more sensitive eating behaviour in response to previous El, both acutely at a test-meal, and for the next 24h. To try to elucidate the mechanisms behind the beneficial role of exercise on appetite control, the effects of 1h of moderate intensity exercise, performed in the fed state, on the plasma levels of appetite-related hormones/metabolites were investigated in normal-weight individuals. Acute exercise significantly increased postprandial levels of polypeptide YY (PYY), glucagon-like peptide-1 (GLP-1) and pancreatic polypeptide (PP) but had no impact on ghrelin, suggesting that exercise can trigger physiological changes in hormone secretion which could help in appetite control and weight maintenance. The role of dietary restraint on the plasma levels of appetite-related hormones/metabolites and subjective/objective measures of appetite was also investigated in normal-weight volunteers. Restraint did not impact on PYY or triacylglycerol (TAG) plasma levels, but was associated with lower fasting insulin plasma levels and a lower release of both insulin and glucose in the postprandial state. Moreover, restrained eaters showed better insulin sensitivity, both fasting and postprandially, and higher fullness ratings in the fed state. Finally, the predictive value of three different questionnaires used to measure restrained eating behaviour (Revised Restrained Scale (RRS), 18-items revised Three Factor Eating Questionnaire (TFEQ-18R) and Dutch Eating Behaviour Questionnaire (DEBQ)) was investigated, in their ability to predict disinhibition in the laboratory in a sample of normal-weight women, using preloads of different energy content and a buffet as the test-meal. None of the questionnaires was able to predict disinhibition; however, the loss of compensation observed with increased levels of restraint was best forecasted by the RRS. Taken together these findings provide strong evidence for a positive role of exercise on appetite regulation and weight maintenance, reinforcing the need to meet current national physical activity targets. The role of dietary restraint in predicting disinhibition seems to be minor; however, this eating behaviour was found to be associated with altered carbohydrate metabolism