Adaptive changes in basal metabolic rate and lean body mass in chronic undernutrition.

The food intake of a group of 14 chronically undernourished unskilled Indian labourers was compared with that of a group of 14 healthy male controls of similar age. Anthropometric and skinfold measurements were used to calculate body mass index (BMI), body surface area (BSA), percentage body fat and lean body mass (LBM). The resting metabolic rate (RMR) was measured 12-14 h after the last meal. The daily energy intake of the controls was 9.46 MJ and of the labourers 6.44 MJ. The controls were taller, heavier, had larger BSA and skinfolds and higher BMIs than the labourers. The average RMR was 26 per cent lower in the labourers in absolute terms, and also per kg body weight/d, per kg LBM/d and per unit BSA, although tests showed that the labourers were physically fit and had satisfactory cardiovascular function. It is concluded that a decreased body weight, adjustments in physical activity and possibly increased metabolic efficiency in energy utilization all contributed to the maintenance of energy balance.