The precise magnitude of the effect of acute exercise on subsequent energy intake is not well understood. Identifying how large a deficit exercise can produce in energy intake and whether this is compensated for, is important in design of long-term exercise programs for weight loss and weight maintenance. Thus, this paper sought to review and perform a meta-analysis on data from the existing literature. Twenty-nine studies, consisting of 51 trials, were identified for inclusion. Exercise duration ranged from 30 to 120min at intensities of 36-81% VO(2)max, with trials ranging from 2 to 14h, and ad libitum test meals offered 0-2h post-exercise. The outcome variables included absolute energy intake and relative energy intake. A random effects model was employed for analysis due to expected heterogeneity. Results indicated that exercise has a trivial effect on absolute energy intake (n=51; ES=0.14, 95% CI: -0.005 to 0.29) and a large effect on relative energy intake (creating an energy deficit, n=25; ES=-1.35, 95% CI: -1.64 to -1.05). Despite variability among studies, results suggest that exercise is effective for producing a short-term energy deficit and that individuals tend not to compensate for the energy expended during exercise in the immediate hours after exercise by altering food intake.

An acute bout of exercise may influence appetite by suppressing levels of acylated ghrelin while simultaneously increasing levels of PYY, GLP-1 and PP, which may contribute to alterations in food and drink intake after acute exercise. Further longitudinal studies and exploration into mechanisms of action are required in order to determine the precise role these hormones play in long-term appetite responses to an exercise intervention.

These results suggest that exercise intensity, mode, duration and the nature of meal/fluid ingested all influence GE during and after acute exercise. The relationship of GE parameters with appetite regulation after exercise remains largely unexplored. Further integrative studies combining GE and alterations in gut hormones, as well as in populations such as overweight and obese individuals are needed.

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