Dietary fatty acid effects on hunger, satiety and metabolism
Stevenson, Jada L.
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Meals high in poly-unsaturated fatty acids (PUFAs) result in greater metabolism compared to saturated fatty acid (SFA) enriched high-fat (HF) meals. Yet, it is unknown what the long-term effects of PUFAs are on metabolism. Purpose: To determine metabolic responses to SFA-rich HF meals before and after a 7d high PUFA diet. Methods: 18, normal weight (BMI=18-24.9kg/m2), sedentary adults were randomly assigned to either a PUFA or control diet. Following a 3d lead-in diet, participants reported for the baseline visit where anthropometrics and resting metabolic rate (RMR) were collected and two SFA-rich HF meals (breakfast and lunch) were consumed. Indirect calorimetry was used determine fat oxidation (Fox) and energy expenditure (EE) for 8h. Participants then consumed a high PUFA (50% carbohydrate, 15% protein, 35% fat, of which 21% of total energy was PUFA, 9% MUFA, 5% SFA) or control diet (50% carbohydrate, 15% protein, 35% fat, of which 7% of total energy was PUFA, 15% MUFA, 13% SFA) for the next 7 days. Following the 7d diet, participants completed the post-visit (same procedures as baseline visit). Results: Following the 7d diets, there was no difference between PUFA vs. control for RMR (16.4±0.8 vs. 16.3±0.8kcal/20min). Fasting respiratory exchange ratio significantly increased from baseline to post-visit in PUFA only (0.83±0.1 to 0.86±0.1, p<0.05). In response to the SFA-rich HF meals, the change in fat oxidation increased from baseline to post-visit in PUFA (0.03±0.1g/15min to 0.23±0.1g/15min for cumulative FOx; p<0.05) with no change in controls. No differences in EE between PUFA vs. control were found. Conclusions: After consuming a 7d PUFA diet, participants oxidized more carbohydrate at fasting but oxidized more fat following the SFA-rich HF meals. Thus, consuming a PUFA diet may help individuals metabolize more fat after the occasional high SFA meal and prevent weight gain in the long-term.