The thermic effect is greater for structured medium- and long-chain triacylglycerols versus long-chain triacylglycerols in healthy young women

The purpose of this study was to investigate the hypothesis that a single d ose of structured medium- and long-chain triacylglycerols (SMLCTs) composed of medium-chain (20%) and long-chain (80%) fatty acids would increase the metabolic rate more than a dose of long-chain triacylglycerols (LCTs) in 15 healthy young women aged 18 to 28 years. The effects on postingestive ener gy expenditure were compared for SMLCTs versus LCTs. On the experimental da ys, the subjects fasted overnight and then ingested 1,680 kJ SMLCTs or LCTs each day. Energy expenditure and the respiratory quotient (RQ) were measur ed before and after SMLCT and LCT ingestion by indirect calorimetry. Blood samples were collected before and after ingestion to obtain plasma and seru m. Postingestive total energy expenditure (PTEE) was significantly higher a fter SMLCT ingestion versus LCT ingestion (26.9 +/- 1.0 v 25.5 +/- 1.1 kJ/k g/6 h, P < .05). The thermic effects of the test oil were also significantl y greater after SMLCT ingestion compared with LCT ingestion (3.02 +/- 0.49 v 1.47 +/- 0.82 kJ/kg/G h, P < .01). Plasma glucose and serum triacylglycer ol concentrations were not significantly different. Serum free fatty acid a nd 3-hydroxybutyric acid concentrations were higher after SMLCT ingestion v ersus LCT ingestion. These results suggest that long-term substitution of S MLCTs for LCTs will produce body fat loss if energy intake remains constant . Copyright (C) 2001 by W.B. Saunders Company.