Seasonality of energy expenditure during pregnancy and lactation for rural Nepali women.

Total energy expenditure (TEE) was estimated for 19 nonpregnant, nonlactating (NPNL) and 24 pregnant (P) or lactating (L) women from 3601 h of minute-by-minute observation and 168 measurements of the energy cost of activities. NPNL women significantly increased subsistence activity and TEE from 9.9 MJ [1.89 x basal metabolic rate (BMR)] in the winter to 10.5 MJ (2.01 x BMR) in the monsoon season. There were differences between NPNL,P, and L women in the winter, but not in the spring or monsoon season when all individuals sustained very heavy physical activity. High TEE values resulted from spending very long hours in tasks that, although appearing physically demanding to the casual observer, were characterized by light or moderate energy cost. The study highlights the importance of seasonal constraints on women's work, which prevent P and L women from significantly curtailing physical activity during the monsoon season, and which effectively limit the scope of behavioral mechanisms for saving energy and reducing TEE.