GLP-1 and appetite responses to a meal in lean and overweight adolescents following exercise

Objective: Increased physical activity is an integral part of weight loss programs in adolescents. We prospectively investigated the effects of exercise on glucagon-like peptide-1 (GLP-1) concentrations and on appetite markers. Methods and Procedures: Normal weight (NW) and at risk of overweight/overweight (OW) male adolescents (n = 17/gr) underwent five consecutive days of aerobic exercise (1 h/day). A test meal was administered prior to the first exercise session and 36 hours following the last exercise session. GLP-1 and markers of appetite were assessed. Results: GLP-1 concentrations over the course of the test meal were lower in OW compared to NW boys (P < 0.05), while fasting GLP-1 concentrations tended to be lower in OW boys (0.05 < P < 0.1). Exercise caused an increase in the acute GLP-1 response to the liquid meal (from 52 to 78%, P = 0.02) that was similar in NW and OW adolescents. OW adolescents expressed greater restraint compared to NW adolescents (three-factor eating questionnaire, TFEQ) and there was a significant correlation between TFEQ for restraint score and BMI s.d. both before and after exercise intervention (P < 0.015). There was no significant correlation between markers of appetite and GLP-1 concentrations. Discussion: Lower concentrations of GLP-1, a satiety hormone, in OW compared to NW male adolescents support the theory that GLP-1 plays a role in the etiology of overweight. Whether the greater meal-induced, 0-30 min GLP-1 response following exercise is associated with increased satiety, a potentially beneficial effect of exercise, needs to be evaluated in larger studies.