Diet composition does not alter energy expenditure, substrate metabolism, or excess post-exercise oxygen consumption in healthy, non-exercise trained women

Dietary intake is thought to influence metabolism during exercise and exercise recovery, yet relatively few studies have addressed these issues. This study examined the influence of a high-carbohydrate (73% of energy) vs high-fat (40% of energy) diet on metabolic responses before, during, and after exercise. Eight female subjects (age, 23.7 ± 4.5 years; height, 162.5 ± 6.8 cm; weight, 56.3 ± 6.6 kg; body fat percentage, 19.6% ± 7.1%; maximal oxygen consumption [VOmax], 30.4 ± 4.8 mL kg−1 min−1) participated in a randomized crossover design including two 5-day dietary interventions. On the morning after each dietary intervention, subjects cycled for 30 minutes at a workload eliciting 70% peak VO2. Respired gases were measured before exercise, during exercise, and throughout recovery. Whole blood lactate and serum concentrations of leptin, free fatty acids, and glucose were assessed at rest and immediately after exercise. There were no significant differences in the respiratory exchange ratio, whole blood lactate concentration, serum concentrations of leptin, free fatty acids, or blood glucose between the feeding trials (P > .05). Duration and magnitude of excess post-exercise oxygen consumption (EPOC) were similar after both diet periods (P > .05). These results indicated that a 5-day dietary adaptation is insufficient to alter EPOC or the metabolic responses assessed at rest and during exercise. These findings indicate that macronutrient composition may have little effect on metabolic measurements, including the calculation of EPOC for the exercise conditions described in the current study.