Evaluation of the role of physical activity levels on the release of appetite-related hormones after preloads with a different energy content

Abstract

Background:Previous research has shown that regular exercisers are able to adjust their energy intake after preloads of different energy content, while inactive individuals are not. However, the mechanisms responsible for the better short-term appetite control in active individuals remain unknown. Purpose: The aim of this study was to look at differences in the release of the appetite hormones in response to preloads of different energy content between active and inactive individuals. Material and Methods: Crossover study with 16 healthy male participants (9 active, 7 inactive), normal- to slightly overweight (BMI 18.5-27 kg/m 2 ) aged 18-50 years. Participants were given a high- (HEP) or a low-energy preload (LEP) for breakfast, in random order, with a wash out period of at least two days and subjective feelings of appetite and the release of appetite-related hormones (active GLP-1, insulin, total PYY and active ghrelin) were measured in response to the intake of both preloads for a period of 2,5 hours. Results: A statistically significant main effect of preload (P<0.001), and physical activity (PA)(P<0.01) and a preload*PA interaction (P<0.001) were found on total area under the curve (tAUC) for insulin plasma levels, with higher insulin levels after the HEP and in inactive participants overall. There was a significant difference between groups for tAUC insulin HEP (P<0.001) but not for LEP, and the difference between preloads was significantly larger in the inactive group (P<0.01). No statistically significant main effects of preload, or PA, or interaction were found for tAUC for total PYY, active ghrelin, or active GLP-1, or subjective feelings of appetite, but active GLP-1 fasting levels were higher in inactive versus active individuals (P<0.05 for HEP and P=0.055 for LEP day). Conclusion: PA seems to modulate the postprandial release of insulin (but not other hormones) after the intake of preloads of different energy content and that may contribute, at least partially, to the differences in short-term appetite control between active and inactive individuals. However, more studies, with larger sample sizes, are needed.