Influence of body fat distribution on free fatty acid metabolism in obesity

In order to determine whether differences in body fat distribution result in specific abnormalities of free fatty acid (FFA) metabolism, palmitate turnover, a measure of systemic adipose tissue lipolysis, was measured in 10 women with upper body obesity, 9 women with lower body obesity, and 8 nonobese women under overnight postabsorptive (basal), epinephrine stimulated and insulin suppressed conditions. Results: Upper body obese women had greater (P < 0.005) basal palmitate turnover than lower body obese or nonobese women (2.8 ± 0.2 vs. 2.1 ± 0.2 vs. 1.8 ± 0.2 μmol·kg lean body mass (LBM)^-1·min^-1, respectively), but a reduced (P < 0.05) net lipolytic response to epinephrine (59 ± 7 vs. 79 ± 5 vs. 81 ± 7 μmol palmitate/kg LBM, respectively). Both types of obesity were associated with impaired suppression of FFA turnover in response to euglycemic hyperinsulinemia compared to non-obese women (P < 0.005). These specific differences in FFA metabolism may reflect adipocyte heterogeneity, which may in turn affect the metabolic abberations associated with different types of obesity. These findings emphasize the need to characterize obese subjects before studies.