Metabolic responses to dietary fatty acids in obese women.

BACKGROUND

The composition of fatty acids in a diet may differentially affect metabolism, thus playing a role in the development of obesity. Our purpose was to study the effects of three high-fat (HF) meals with different dietary fatty acid compositions on the thermic effect of meal (TEM) and substrate oxidation in obese premenopausal women.

METHODS

16 healthy obese women, aged 18-39 years, participated in a single-blinded randomized cross-over study, in which they consumed isocaloric HF meals (70% of energy from fat) rich in either saturated fat (SFA), monounsaturated fat (MUFA) or polyunsaturated fat (PUFA). Indirect calorimetry was used to measure respiratory gases for a 5-hour postprandial period. Data collected was used to determine respiratory exchange ratio (RER) for assessing substrate oxidation, and energy expenditure for the determination of TEM.

RESULTS

There was a significant time effect on both substrate oxidation and TEM (p<0.05). With and without using RMR as a covariate, there were no significant differences in TEM between test meals (TEM of 10.8±0.8 vs 11.0±1.0 kcal ∗ 5 h for high-MUFA vs. high-SFA meals, respectively, p=0.06). No treatment difference was found for postprandial substrate utilization (4.9±0.4, 4.9±0.3 and 4.6±0.4 g of fat oxidation following SFA, MUFA, and PUFA-rich HF meals, respectively; 13.2±0.9, 13.3±0.5 and 13.9±0.6 g of carbohydrate oxidation following SFA, MUFA, and PUFA-rich HF meals, respectively).

CONCLUSIONS

In premenopausal obese women, HF meals rich in either MUFAs, PUFAs, or SFAs did not differentially affect TEM or postprandial substrate oxidation.