Decreased Appetite after High-Intensity Exercise Correlates with Increased Plasma Interleukin-6 in Normal-Weight and Overweight/Obese Boys.

: High-intensity exercise (HIEX) suppresses appetite in adults and is thought to be mediated by appetite-regulating hormones. However, the effects of HIEX-induced inflammatory and stress biomarkers on appetite control and body weight have not been reported in children or adults. The objective of this study was to describe the effects of acute HIEX at 70% peak oxygen consumption (VO) on postexercise appetite and selective biomarkers of inflammation, stress, and appetite regulatory hormones in normal-weight (NW) and in overweight/obese boys. NW ( = 11) and overweight/obese ( = 11) boys aged 10-18 y were randomly assigned in a crossover design to either rest or HIEX. Visual analog scale appetite ratings and plasma biomarkers of appetite, inflammation, stress, and glucose control were measured after HIEX or rest. Appetite increased from baseline to 110 min ( < 0.001), but was lower after HIEX ( = 0.04), with no difference between body weight groups. HIEX also resulted in lower active ghrelin ( < 0.001) and increased interleukin-6 (IL-6; < 0.001), tumor necrosis factor-α ( < 0.001), and cortisol ( < 0.001) concentrations, independent of body weight. It increased blood glucose ( = 0.002) and insulin ( = 0.028) concentrations in NW but not overweight and obese boys. Leptin, glucagon-like peptide 1, peptide tyrosine tyrosine, C-reactive protein, and cortisol were not affected by HIEX. An inverse correlation was found between IL-6 and appetite ( = -0.379; = 0.012), but not any other biomarkers. HIEX resulted in reduced appetite that correlated with an increase in IL-6 in both NW and overweight/obese boys. However, although a role for IL-6 in the response can be suggested, the suppression of appetite was potentially mediated by the decrease in active ghrelin and/or increase in cortisol. This trial was registered at clinicaltrials.gov as NCT02619461.