POSTPRANDIAL THERMOGENESIS AND SUBSTRATE UTILIZATION AFTER INGESTION OF DIFFERENT DIETARY CARBOHYDRATES

Whole-body thermogenesis, substrate utilization (open-circuit ventilat ed-hood system), and exogenous carbohydrate oxidation were evaluated i n 10 healthy lean male volunteers (aged 27.8 +/- 2.5 years) for 6 hour s after oral ingestion of 75 g naturally enriched fructose, glucose (b oth derived from corn starch), cane sugar, and a good digestible corn starch (all mixed with 400 mt water). The integrated areas under the g lucose and insulin response curves above baseline were highest with gl ucose and starch, intermediate with sucrose, and lowest with fructose, whereas there were no significant differences in the integrated nones terified fatty acid (NEFA) response between carbohydrates. The total i ncrement in energy expenditure (EE) above baseline was similar with fr uctose (130 +/- 24 kJ/6 h) and sucrose (141 +/- 17 kJ/6 h), was higher with sucrose as compared with starch (108 +/- 24 kJ/6 h, P < .05) and glucose (94 +/- 20 kJ/6 h, P < .05), and tended to be higher with fru ctose as compared with glucose (P = .059). Both the increment in total carbohydrate oxidation (P < .05) and the increment in exogenous carbo hydrate oxidation (P < .01) were significantly higher with fructose an d sucrose compared with glucose and starch. The initial inhibition of lipid oxidation was higher with sucrose and fructose than with glucose and starch, whereas the integrated decrement in lipid oxidation over 6 hours was only higher with fructose compared with glucose and starch (P < .05). In conclusion, thermogenesis and substrate utilization var y considerably after ingestion of different types of carbohydrate in y oung lean males, indicating that the carbohydrate composition of the d iet may have important consequences for energy and macronutrient balan ce. Copyright (C) 1996 hy W.B. Saunders Company