Enhanced postprandial energy expenditure with medium-chain fatty acid feeding is attenuated after 14 d in premenopausal women.
BACKGROUND
Medium-chain triacylglycerols (MCTs) are reported to enhance human energy expenditure (EE), although few studies have involved women and the duration of such effects is only known for periods of approximately 7 d.


OBJECTIVE
This study was conducted to determine whether women consuming mixed, MCT-enriched or long-chain triacylglycerol (LCT)-enriched diets showed changes in EE or substrate oxidation after 7 and 14 d.


METHODS
Twelve nonobese, premenopausal women were fed isoenergetic mixed diets enriched in either MCTs or LCTs during separate, 14-d feeding periods. Each meal contained 40% of energy as fat (80% of which was the treatment fat), 45% as carbohydrate, and 15% as protein. On days 7 and 14 of each trial, basal metabolic rate (BMR, kJ/min), total energy expenditure (TEE, kJ/min), and thermic effect of feeding (deltakJ/min) after a standardized breakfast were measured by respiratory gas exchange.


RESULTS
On day 7, the mean (+/-SEM) BMR (3.58+/-0.11 kJ/min) with the MCT diet was greater (P = 0.0003) than that with the LCT diet (3.43+/-0.11 kJ/min). The mean postprandial TEE on day 7 was significantly greater (P = 0.04) with the MCT diet (4.36+/-0.04 kJ/min) than with the LCT diet (4.23+/-0.04 kJ/min); by day 14, postprandial TEE was still greater with the MCT diet, but not significantly so. No significant differences in the thermic effect of feeding were evident between diets.


CONCLUSIONS
Results from this longest controlled MCT feeding study to date suggest that short-term feeding of MCT-enriched diets increases TEE, but this effect could be transient with continued feeding.
White
M D
MD
School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, Quebec, Canada.
Papamandjaris
A A
AA
Jones
P J
PJ
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D002245:Carbon Dioxide / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage*; D004734:Energy Metabolism; D005227:Fatty Acids / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D010101:Oxygen Consumption; D019518:Postprandial Period; D017697:Premenopause / Q000378:metabolism*; D013997:Time Factors
D004041:Dietary Fats; D005227:Fatty Acids; D002245:Carbon Dioxide