Does Vo2peak Moderate The Association Between Dietary Fat Intake And Post-prandial Fat Oxidation?

Abstract

Previous evidence suggests that individuals with low fat oxidation rates at rest may be prone to developing obesity and diabetes. Both exercise training and a high-fat diet are known to increase fat oxidation. It is unclear, however, whether exercise training influences the relationship between dietary fat intake and post-prandial (PP) fat oxidation. PUPROSE: The purpose of this study was to determine whether VO2peak moderates the association between dietary fat intake and PP fat oxidation after a high-fat meal. METHODS: Twenty-nine healthy young adults (17 M, aged 19–38 yrs) of varying aerobic capacities (VO2peak= 49.4±11.1 ml/kg/min) were randomized to either a moderate-intensity walking or sedentary condition. In the EX condition, walking was performed 60min PP (EX, energy expenditure 50% of breakfast kcals). After a 12hr fast, all participants consumed a high-fat breakfast (65% fat, 10 kcal/kgbw). Resting metabolic rate was assessed immediately after, and 200min following, consumption of the high-fat meal. Assessments included dietary fat via 3-day food log, VO2peak with a treadmill ramp protocol to exhaustion, indirect calorimetry with a ventilated hood system to determine fat oxidation at 0min and 200min PP, and %body fat via DEXA. RESULTS: Dietary fat intake was 798.6±235.4 kcal/day. Fat oxidation at baseline was not different from 200min PP (47.9±16.4 vs. 50.7±17.8 kcal/hr, p>0.05). There was a significant correlation between dietary fat intake and 200min PP fat oxidation (r=0.37, p<0.05) and between VO2peak and 200min PP fat oxidation (r=0.62, p<0.01). Moderation analysis examining the effect of VO2peak on the association between dietary fat intake and PP fat oxidation revealed no significant moderation (ΔR2=0.007, p=0.60). A subsequent linear regression, including VO2peak, dietary fat intake, %body fat, baseline fat oxidation, and energy balance PP (kcals); predicted 79% of the variance in PP fat oxidation (adjusted R2= 0.79, p<0.001). CONCLUSION: VO2peak did not moderate the association between dietary fat intake and PP fat oxidation. When examining additional factors thought to be associated with fat oxidation, however, 79% of the variance in PP fat oxidation was explained. These results indicate that post-prandial fat oxidation is a complex process with multiple contributing factors.