Elevated postprandial lipemia (PPL) is associated with impaired endothelial function, an increase in adhesion molecule expression and inflammation. Acute exercise reduces PPL in adults. No studies have examined the effect of acute exercise on PPL in normal weight (NW) and overweight (OW) adolescents. PURPOSE: To investigate the effect of an acute bout of exercise (600 kcal) on postprandial changes in triglycerides (TG), glucose, insulin, adhesion molecules (sICAM-1, sVCAM-1) and inflammatory markers (CRP, IL-6, TNF-α, WBC) following a high-fat meal in NW and OW adolescents. METHODS: 10 NW (BMI: 20.9 ± 1.7 kg.m-2, 15.6 ± 0.7 y) and 8 OW (BMI: 28.3 ± 3.6 kg.m-2, 15.9 ± 0.4 y) adolescent boys underwent two 6h oral fat tolerance tests (OFTT) separated by 7 d. On the evening prior to each OFTT, subjects rested (CTL) or completed a treadmill walk/run at 70% VO2max until 600 kcal had been expended (EX). Blood samples were obtained at baseline and at 30 min, 1, 2, 4 and 6 h after eating. RESULTS: Exercise reduced (p<0.01) the postprandial TG area under the curve by ~25% in both the NW and OW groups. The postprandial glucose and insulin response did not differ between the control and exercise trials or between the NW and OW groups. Circulating leukocytes and plasma IL-6 levels increased (p<0.01) in the NW and OW groups 6 h following the OFTT in both experimental conditions. Plasma concentrations of TNF-α were higher (p<0.05) in the OW than the NW group at rest and 6 h following the OFTT in both the control and exercise experimental condition. There were no changes in CRP, sVCAM-1 or sICAM-1 following the OFTT and there were no differences between experimental condition or BMI group. CONCLUSION: Acute exercise attenuates the postprandial TG response to a high-fat meal similarly in NW and OW adolescents but does not reduce inflammation or alter adhesion molecule expression in the postprandial period.