IMMEDIATE METABOLIC AVAILABILITY OF DIETARY-FAT IN COMBINATION WITH CARBOHYDRATE

We tested the hypothesis that when fat is ingested in combination with carbohydrate, direct release of fatty acids into the plasma may occur . Eight normal subjects ingested two meals: high-fat (80 g fat, 80 g c arbohydrate, and 18 g protein) and low-fat (<1g fat, otherwise closely matched). Over the subsequent 6 h, net fat oxidation was greater afte r the high-fat meal (20.7 vs 10.6 g, P<0.01). Plasma nonesterified fat ty acid (NEFA) concentrations were markedly suppressed after the lowfa t meal, but relatively maintained after the high-fat meal (P<0.01). Th e profile of plasma NEFAs changed after the high-fat meal, consistent with entry of meal-derived fatty acids into the NEFA pool. We suggest that after ingestion of combinations of carbohydrate and fat, the acti on of lipoprotein lipase on chylomicron-triacylglycerol leads to direc t release of fatty acids into the plasma and increased fat oxidation.