EXERCISE-INDUCED SUPPRESSION OF APPETITE - EFFECTS ON FOOD-INTAKE ANDIMPLICATIONS FOR ENERGY-BALANCE

Objective: To examine the effects of exercise on short term energy int ake and to investigate the existence of exercise-induced anorexia. Des ign: Two studies were conducted, both with three treatment conditions and employing a repeated measures design. Setting: The Human Appetite Research Unit at Leeds University Psychology department. Subjects: Twe nty three healthy, lean male subjects (n = 11 and n = 12 respectively) were recruited from the student/staff population of Leeds University. Interventions: Subjects were randomly assigned to a control, low inte nsity and high intensity exercise treatment in the first study and to a control, short duration and long duration exercise treatment (high i ntensity) in the second. Motivation to eat was measured by visual anal ogue rating scales and by the length of the time between the end of ex ercise and the volitional onset of eating. Energy and macronutrient in takes were measured by means of a free-selection test meal and by reco rded intakes for the next 2 days. Results: Subjective feelings of hung er were significantly suppressed during and after intense exercise ses sions (P < 0.01), but the suppression was short-lived. Exercise sessio ns had no significant effect on the total amount of food consumed in t he test meal but intense exercise delayed the start of eating (P < 0.0 5). When energy intake was assessed relative to the energy expended du ring the exercise or control periods, only the long duration, high int ensity session created a significant short-term negative energy balanc e (P < 0.001). Conclusions: These studies indicate that exercise-induc ed anorexia can be characterized by a brief suppression of hunger, acc ompanied by a delay to the onset of eating. The temporal aspects of ex ercise-induced anorexia may best be measured by the resistance to begi n eating rather than the amount of food consumed.