Enhanced dietary fat clearance in postobese women

Abstract

The objective of this study was to examine the postprandial response toan exogenous fat source in eight weight-stable postobese subjects (2–3years after gastric bypass) and eight matched control women, using a stableisotope, [13C]oleate. After a high fat breakfast meal (1,062 cal, 67%fat), [13C]oleate in triglyceride (TG)-rich lipoproteins(Sf >400 and Sf 20–400) andnonesterified fatty acids (NEFA), and 13C in breath CO2,were monitored over 8 h. There were no differences in resting energyexpenditure, thermic effect of food, carbohydrate/fat oxidation ratio, breath13CO2 enrichment, or fecal fat content betweenpostobese and control subjects. Postprandially, there was no difference inSf 20–400 TG or NEFA, but postobese subjects had lowerSf >400 incremental area under the curve (AUC)(−33%, P 400 TGreturned to fasting levels 4 h earlier in postobese subjects and was lower thanin control subjects at 4 and 6 h (P < 0.05 by RMANOVA). The greatest difference was in the [13C]NEFA profiles. Incontrol subjects [13C]NEFA increased markedly over 8 h; postobesesubject [13C]NEFA remained close to fasting nonenriched values, andwas strikingly lower than in control subjects (72% lower by AUC,P < 0.0001 by RM ANOVA). Finally, postobesesubjects tended to have lower postprandial insulin (P <0.01, 4 h), lower postprandial acylation-stimulating protein, and lower fastingleptin (−46%, P < 0.02). This studydemonstrates clear metabolic differences in exogenous dietary fat partitioningin postobese women. These findings are compatible with an increased efficiencyof dietary fat storage and suggest one possible mechanism for promotion ofweight regain in postobese individuals. —Faraj, M., P. Jones, A. D. Sniderman, and K. Cianflone. Enhanceddietary fat clearance in postobese women. J. Lipid Res. 2001.42: 571–580.

Keywords

• triglyceride
• C3adesArg
• stable isotope
• [13C]oleate
• nonesterified fatty acid
• insulin