Seven-Day Caloric and Saturated Fat Restriction Increases Myocardial Dietary Fatty Acid Partitioning in Impaired Glucose-Tolerant Subjects

Subjects with impaired glucose tolerance (IGT) have increased myocardial partitioning of dietary fatty acids (DFA) with left ventricular dysfunction that are improved by modest weight loss over one year induced by lifestyle changes. Here, we determined the effects of a 7-days hypocaloric diet (-500 kcal/d) low in saturated fat ( vs. isocaloric with usual saturated fat (∼10% of energy) diet (ISOCAL) on DFA metabolism in IGT subjects. Organ-specific DFA partitioning and cardiac and hepatic DFA fractional uptake rates were measured in 15 IGT subjects (7M/8F) using the oral 18-Fluoro-6-thia-heptadecanoic acid positron emission tomography method ([ 18 F]-FTHA) after 7 days of ISOCAL vs. LOWCAL diet using a randomized crossover design. LOWCAL led to reduction in weight and reduction in postprandial insulin AUC. Myocardial DFA partitioning over 6 hours was increased after LOWCAL (2.3±0.1 vs. 1.9±0.2 SUV, P vs. 0.046±0.009 min -1 , P =0.7). Liver DFA partitioning was unchanged, but liver fractional uptake of DFA tended to be increased. Very short-term caloric and saturated fat dietary restriction does not lead to the same changes in organ-specific DFA metabolism than those associated with weight loss in IGT.