Postprandial Free Fatty Acid Kinetics Are Abnormal in Upper Body Obesity

Excess free fatty acid release (rate of appearance) is seen in overnight postabsorptive, upper body obese women and, if present postprandially, could contribute to glucose intolerance. These studies examine the antilipolytic effect of a mixed meal in upper body obese, lower body obese, and nonobese women and the contribution of meal triglyceride fatty acids to circulating free fatty acids. Eight upper body obese, 8 lower body obese, and 8 nonobese age-matched, premenopausal women were studied. Systemic oleate R_a ([³H]oleate) was measured before and after an evening meal that contained triolein labeled with [¹⁴C]triolein as the only source of fat. Premeal oleate R_a was greater in both upper body obese and lower body obese women than nonobese women. The nadir of total oleate R_a occurred 90–240 min postprandially and was less (P < 0.01) in nonobese and lower body obese women (63 ± 10 and 87 ± 17 μmol/min) than in upper body obese women (140 ± 21 μmol/min). Meal oleate R_a contributed substantially to total oleate R_a. The nadir for endogenous oleate R_a in nonobese and lower body obese women was less (P < 0.01) than that observed in upper body obese women. We conclude that the antilipolytic effect of a mixed meal is reduced in upper body obese women and that meal triglyceride fatty acids contribute significantly to postprandial free fatty acid flux.