Differences in substrate metabolism between self-perceived 'large-eating' and 'small-eating' women.

OBJECTIVE: To compare different aspects of intermediary metabolism in self perceived «small-eating» females and self-perceived near normal weight «large-eating» females and relate the data to those reported for Pima Indians who have the world's highest prevalence of non-insulin dependent diabetes mellitus and obesity. DESIGN: Make repeat measurements of rates of oxygen consumption, carbon dioxide prodluction and blood metabolites in «large-» and «small-eating» females at rest, during different activities and after ingestion of a standardised liquid meal. SUBJECTS: Nine self perceived, large-eating females and nine self perceived small-eating females. MEASUREMENTS: Resting metabolic rates (RMR), respiratory quotient (RQ) values and plasma insulin, glucagion insulin-like growth factor (IGF-1), dehydroepiandrosterone sulphate (DHEA-Q 4 ) and glucose. RESULTS: RMR (adjusted for FFM) averaged 3891±93 J/min in the small-eaters and 3375±107 J/min in the large-eaters for ten consecutive measurements conducted at 30 min intervals during the control period for the measurement of the thermic effect of food. Over this period the average RQ for the small-eating women (0.81) was significantly greater than that of the large-eating women (0.78). The two groups responded similarly to an oral glucose tolerance test but the concentration of DHEA-SO 2 in plasma was 35% higher in the small-eaters. CONCLUSION: The small-eating women may have a greater risk of greater risk of weight gain but they counteract this tendency by maintainingh high activity levels