COMPONENTS OF POSTPRANDIAL THERMOGENESIS IN RELATION TO MEAL FREQUENCY IN HUMANS

Experiments on dogs have shown that the size of the meal has no effect on the early cephalic postprandial thermogenesis, and that four small meals are more thermogenic than a larger meal with the same total cal oric content as the four meals. A study was repeated on human subjects who were fed during alternating weeks either one large meal (653 kcal (1 kcal = 4.1855 kJ)) or four small meals (163 kcal) at 40-min interv als. Oxygen consumption and respiratory exchange ratio determinations indicated (i) larger overall increase in postprandial thermogenesis wi th the four meals than with one meal and (ii) an enhancement of glucos e utilization with the large meal compared with greater lipid utilizat ion with the four meals. On the basis of indirect evidence from previo us investigations it is suggested that the enhanced thermogenesis obse rved in the four-meal experiment is due to lipid mobilization caused b y repeated stimulation of the sympathetic nervous system with palatabl e food. Blood analysis indicated a reduced elevation of plasma glucose in the four-meal experiment. The variations of insulin and C-peptide exactly paralleled those observed for glucose. It is concluded that th e increased frequency of feeding significantly reduces insulin secreti on in subjects fed a relatively high carbohydrate meal. In addition to this beneficial effect, increasing the number of meals increased ther mogenesis and fat utilization.