Abstract 4135: The Effects of Brief Overnutrition on Postprandial Fuel Metabolism
We have previously shown that 3 days of overfeeding results in relative insulin resistance. We wondered whether the metabolic response to a meal would also be altered following brief overnutrition. As part of the Energy Adaptations over Time Study (EATS) healthy men (n=13) and women (n=14) ages 25–35 were empirically classified as obesity prone (OP, n=13) or obesity resistant (OR, n=14) based on family and personal weight history. On 2 occasions, separated by at least 1 month, subjects were studied while they consumed, in random order, either a controlled eucaloric or hypercaloric (1.4 x basal energy) diet for 3 days. These diet periods were preceded by 4 days of eucaloric run-in diet to ensure energy and nutrient balance. All diets were of identical composition (30% fat, 20% protein, 50% carbohydrate). On the 3rd day of both controlled diet periods (eucaloric, overfeeding) previously fasted subjects consumed a liquid test meal containing 30% of daily energy. Glucose, insulin, free fatty acid (FFA) and triglyceride concentrations were measured in the fasting state and every 30 minutes after the test meal for 270 minutes. Baseline evaluations, both fasting and postprandial area under the curve (AUC), were similar between groups except for FFA AUC which was higher in OP individuals (OP: 2,983±144 vs 2,353±139, p=0.02). Overfeeding resulted in an increase in fasting glucose (79.6±1.8 to 85.0±1.7, p=0.005) but not in glucose AUC. Although not different in the fasted state, overfeeding resulted in a highly significant increase in insulin AUC (108.9±8.8 to 148.50±12.1, p<0.001). Both fasting FFA (577±39 to 429±23, p=0.001) and FFA AUC (2,656±162 to 1,935±107, p<0.001) decreased with overfeeding. Postprandial triglyceride excursion rose significantly with overfeeding (822±84 to 968±78, p=0.003). No group differences were seen in the glucose, insulin or FFA responses to overfeeding. Postprandial triglyceride excursion, however, only rose with overfeeding in the OP individuals (p=0.047 between groups). Short periods of overnutrition appear to result in postprandial hyperinsulinemia that may represent insulin resistance. OP individuals appear to be predisposed to increases in postprandial triglyceride excursions following overfeeding.