Resting metabolic rate and work efficiency of rural Beninese women: a 2-y longitudinal study.

This study was performed on 34 female farmers in northern Benin during 2 consecutive years. Body composition, energy intake, energy expenditure, resting metabolic rate (RMR), and energy cost of cycling on a bicycle were measured in three periods per year. Energy intake showed seasonal fluctuations of approximately 1.7 MJ/d in 1990 and 0.6 MJ/d in 1991. Body weight fluctuated between periods, with the lowest weight in preharvest periods. Observed changes in body weight were 2.6 +/- 2.3 and 0.9 +/- 1.7 kg in 1990 and 1991, respectively. The same pattern was observed in both fat mass and fat-free mass. RMR, energy cost of cycling, and delta work efficiency did not show any seasonal changes. It is concluded that metabolic adaptation, as a response to a seasonal food shortage up to 15% of average daily intake, will not occur.