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 production 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, glucagon insulin-like growth factor (IGF-1), dehydroepiandrosterone sulphate (DHEA-SO4) 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-SO4 in plasma was 35% higher in the 'small-eaters'.

CONCLUSION

The 'small-eating' women may have a greater risk of weight gain but they counteract this tendency by maintaining high activity levels.