|RUST, BRET - Former ARS Employee|
|RAATZ, SUSAN - Former ARS Employee|
Submitted to: Nutrients
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2021
Publication Date: N/A
Interpretive Summary: Obesity is growing medical problem in the United States and many countries. Increasing energy expenditure and/or lowering energy intake may assist in reduce obesity rates. In the American diet, fats make up about 30% of the energy eaten daily. Increasing data show that the metabolic effects of fats can differ because of the chemical structure of the fat. In this work, we studied whether the chemical composition (fatty acid size and saturation level) of different, commercially available dietary fats influence energy expenditure, the desire to eat, and fullness in the short term (four hours) following a single meal made with the different fats. These fats included dairy cream, olive oil, sunflower oil, flaxseed oil, and fish oil that are enriched with either saturated fatty acids, oleic acid, the omega-6 linoleic acid, the omega-3 alpha-linolenic acid, or the longer chain omega-3 fatty acids, respectively. We found that the dietary fat types did not differ in their ability to change energy expenditure or feelings of hunger or fullness in the four-hour period following the single meal. While longer term studies are needed, our data demonstrate that changing the dietary fat type of a single meal will not acutely modify endpoints associated with obesity reduction. These findings have great value for clinicians, nutritionists, and research scientists.
Technical Abstract: Background: Structural differences in dietary fatty acids modify their rate of oxidation and effect on satiety, endpoints that may influence the development of obesity. Objective: This study tests the hypothesis that meals containing unsaturated fats have greater postprandial energy expenditure, fat oxidation and satiety than meals containing fats with greater saturation. Methods: In a randomized, 5-way cross-over design, healthy men and women (n = 23; age: 25.7 ± 6.6 yrs; BMI: 27.7 ± 3.8 kg/m2) consumed liquid meals containing fat sources enriched in saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), or polyunsaturated fats (PUFA). PUFA sources were enriched in linoleic acid (LA), alpha-linolenic acid (ALA), or long-chain n-3 PUFA acids (LCn-3). Primary outcomes included energy metabolism, diet-induced thermogenesis (DIT) and substrate oxidation measured in a whole-room calorimeter, and subjective measures of satiety. Serum concentrations of ghrelin, glucose, insulin and triacylglycerol (TAG) were assessed for 240 min following meal intake. Results: DIT and substrate oxidation did not differ among fats over the entire postprandial period although some differences in energy metabolism were noted between individual fats at specific time points. Subjective measures of satiety were unaffected by dietary fat type. Postprandial elevations in TAG were greatest following the SFA meal; however, other postprandial serum responses were not modulated by dietary fat type. Conclusions: Varying the fatty acid chain length, degree of saturation, or PUFA type did not modify postprandial energetic or satiety responses although differences in postprandial lipemia did occur. These data indicate that dietary fat type does not differentially impact energy balance in an acute manner following a single meal. The study was registered at www.ClinicalTrials.gov (NCT02496936).