Are post-exercise plasma glucose elevations involved in exercise-induced appetite suppression?

Changes in glucose and insulin are potentially involved in the appetite-regulatory effects of exercise considering their role post-prandially. The purpose of this study was to examine whether glucose and insulin play a role in post-exercise appetite regulation. Twelve participants (M = 8; 26 ± 5 years) completed 3 experimental sessions in a systematically rotated randomized crossover design: (1) no-exercise control (CTRL); (2) moderate-intensity continuous training (MICT; 30 min, 70% maximal oxygen consumption (V̇O_2max)); and (3) sprint interval training (SIT; 4 × 30 s "all-out" sprints, interspersed with 4 min rest). Plasma glucose, insulin, acylated ghrelin, active peptide tyrosine tyrosine (PYY), active glucagon-like peptide-1 (GLP-1), and overall appetite perceptions were measured pre-exercise, 0, 30, 60, and 120 min post-exercise. Energy intake was recorded the day before, of, and after experimental sessions. Glucose was elevated 0 min post-exercise (p < 0.097, d > 0.52) compared to CTRL with no differences between exercise bouts. Acylated ghrelin was suppressed by MICT (60, 120 min) and SIT (0, 30, 60, 120 min; p < 0.080, d > 0.56) compared to CTRL, while also suppressed in SIT compared to MICT at 30, 60, 120 min (p < 0.026, d > 0.74). GLP-1 was elevated following MICT (0, 30, and 60 min) and SIT (60 min; p < 0.094, d > 0.53) compared to CTRL and following MICT compared to SIT (0 min; p = 0.005, d = 1.03). Overall appetite was suppressed by SIT post-exercise (p < 0.058, d > 0.61) compared to CTRL and MICT, and by MICT 0 min post-exercise compared to CTRL (p = 0.036, d = 0.71). There were no exercise effects on insulin, PYY, or free-living energy intake (p > 0.217, η_p ² < 0.130). Glucose and insulin do not appear to play a role in exercise-induced appetite suppression.