Predicting energy requirements: is energy expenditure proportional to the BMR or to body weight? An analysis of data collected in rural Gambian women.

It has been suggested that energy requirements are either proportional to the BMR (FAO/WHO/UNU, 1985) or to body weight (WHO, 1973). The present analysis sought to distinguish between these two possibilities by determining whether, in rural Gambian women, energy expenditure was more nearly proportional to the BMR or to body weight. For nine of eleven common daily activities energy expenditure expressed per kg body weight was significantly lower in heavier compared to lighter individuals, indicating that energy expenditure was not proportional to weight. Since, in a preliminary analysis, it was found that in Gambian women BMR was roughly proportional to weight raised to the power 0.5, energy expenditure was also compared per kg. For ten of the eleven activities there were no significant differences between different weight groups in the energy costs expressed per kg, and it follows from this that in Gambian women the energy cost of common daily activities was more nearly proportional to the BMR than it was to body weight. Possible reasons for and implications of these results are discussed.