Effects of training status on the metabolic responses to high carbohydrateand high fat meals

The purpose of this study was to determine if there is a difference between the way in which aerobically trained and untrained women metabolize fats a nd carbohydrates at rest in response to either a high-fat or high-carbohydr ate meal. Subjects, 6 per group, were fed a high CHO meal (2068 kJ, 76% CHO , 23% fat, 5% protein) and a high fat meal (2093 kJ, 21% CHO, 72% fat, 8% p rotein) in counterbalanced order. Resting metabolic rate (RMR) was measured every half-hour for 5 hours. RMR was similar between groups. Training stat us had no overall effect on postprandial metabolic rate or total energy exp enditure. The high fat meal resulted in no significant differences in RMR o r respiratory exchange ratio (RER) between groups. However, after ingesting a high CHO meal, trained subjects had a peak in metabolism at minute 60, n ot evident in the untrained subjects. In addition, postprandial RER from mi nutes 120-300 were lower and fat use was greater after the high CHO meal fo r the trained subjects. These results suggest that aerobically trained wome n have an accelerated CHO uptake and overall lower CHO oxidation following the ingestion of a high CHO meal.