Metabolic responses to high-fat diets rich in MUFA v. PUFA.
Study Goal
The researchers aimed to compare the metabolic effects of a 5-day high-fat diet rich in polyunsaturated fatty acids (PUFA) versus monounsaturated fatty acids (MUFA) in normal-weight men.
Results Summary
The study found that a MUFA-rich meal acutely resulted in lower respiratory exchange ratio (RER) and greater diet-induced thermogenesis (DIT), while a 5-day PUFA-rich diet led to greater changes in metabolic responses, including RER and fat oxidation, suggesting metabolic adaptability to PUFA.
Population
Fifteen normal-weight men.
Effective Dosage
50% fat diet (25% of energy from PUFA or MUFA).
Duration
5 days per diet (plus a 3-day lead-in diet).
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
5-d diet rich in PUFA | no change | fasting metabolism | fifteen normal-weight men | no significant change | There were no treatment differences | #1 |
5-d diet rich in MUFA | no change | fasting metabolism | fifteen normal-weight men | no significant change | There were no treatment differences | #2 |
PUFA-rich meal | increase | RER | fifteen normal-weight men | 0·86 (sem 0·01) v. 0·84 (sem 0·01) | RER was higher for PUFA v. MUFA | #3 |
PUFA-rich meal | decrease | diet-induced thermogenesis (DIT) | fifteen normal-weight men | 18·91 (SEM 1·46) v. 21·46 (SEM 1·34) kJ | diet-induced thermogenesis (DIT) was lower for PUFA v. MUFA | #4 |
5-d PUFA-rich diet | decrease | change in RER | fifteen normal-weight men | -0·02 (sem 0·01) v. 0·00 (sem 0·01) | the change in RER was different for PUFA v. MUFA | #5 |
5-d PUFA-rich diet | increase | change in fat oxidation | fifteen normal-weight men | 0·18 (sem 0·07) v. 0·04 (sem 0·06) g | the change in fat oxidation was greater for PUFA v. MUFA | #6 |
MUFA-rich meal | decrease | RER | fifteen normal-weight men | - | results in lower RER | #7 |
MUFA-rich meal | increase | diet-induced thermogenesis (DIT) | fifteen normal-weight men | - | results in greater DIT | #8 |
5-d PUFA-rich diet | increase | change in metabolic responses | fifteen normal-weight men | - | the change in metabolic responses was greater | #9 |
Dietary fatty acid (FA) composition may influence metabolism, possibly affecting weight management. The purpose of this study was to compare the effects of a 5-d diet rich in PUFA v. MUFA. A total of fifteen normal-weight men participated in a randomised cross-over design with two feeding trials (3 d lead-in diet, pre-diet visit, 5-d PUFA- or MUFA-rich diet, post-diet visit). The 5-d diets (50 % fat) were rich in either PUFA (25 % of energy) or MUFA (25 % of energy). At pre- and post-diet visits, subjects consumed breakfast and lunch test meals, rich in the FA for that 5-d diet. Indirect calorimetry was used for 4 h after each meal. There were no treatment differences in fasting metabolism acutely or after the 5-d diet. For acute meal responses before diet, RER was higher for PUFA v. MUFA (0·86 (sem 0·01) v. 0·84 (sem 0·01), P<0·05), whereas diet-induced thermogenesis (DIT) was lower for PUFA v. MUFA (18·91 (SEM 1·46) v. 21·46 (SEM 1·34) kJ, P<0·05). After the 5-d diets, the change in RER was different for PUFA v. MUFA (-0·02 (sem 0·01) v. 0·00 (sem 0·01), P<0·05). Similarly, the change in fat oxidation was greater for PUFA v. MUFA (0·18 (sem 0·07) v. 0·04 (sem 0·06) g, P<0·05). In conclusion, acutely, a MUFA-rich meal results in lower RER and greater DIT. However, after a 5-d high-fat diet, the change in metabolic responses was greater in the PUFA diet, showing the metabolic adaptability of a PUFA-rich diet.