1. Food intake and energy expenditure were determined on 500 soldiers drawn from infantry, artillery and engineer units of the Indian army, for 3 months during winter..
2. The units were located in two different regions of India at altitudes varying from sea level to 2300 m..
3. The energy requirements were assessed from the actual food intake as well as from energy expenditure and from the changes in body-weight and skinfold thickness..
4. The nutritional adequacy of the diet was assessed from clinical examination and changes in blood haemoglobin concentration..
5. The mean energy expenditure was found to be 15.39 MJ (3679 kcal) and on this basis the energy requirement was 16.61 MJ (3970 kcal); energy intake was found to be 16.47 MJ (3936 kcal)..
6. The energy contributed by protein, fat and carbohydrate was 0.115, 0.240 and 0.645 of the total intake respectively..
7. There was no significant change in body-weight, blood haemoglobin level and skinfold thickness on this mean daily intake.