1. Body-weight, skinfold thickness and food intake were measured at regular intervals in twenty-five young men while on an Antarctic expedition.
2. The mean calorie intake over the year was 3600 kcal/man per day; 12.1% of these calories were supplied by protein, 39.8% by fat, and 48.1% by carbohydrate.
3. The calorie intake was equivalent to that which would be expected in a moderately active worker living in a temperate climate. The chemical composition of the diets did not differ from average values for young men in the United Kingdom.
4. There was a significant fall in food intake during the winter months, when the outside temperatures were greatly reduced and there was polar night. During this period the men were largely confined to the limits of the base hut and the levels of physical activity showed a marked fall.
5. During the year there was a gain in body-weight of 2.7 kg. Of this gain 2.5 kg occurred in the first 2 months.
6. Skinfold thickness followed the trend of the body-weights except for the April-May increment which was unaccompanied by a weight change. This dissociation could not be explained.