There have been relatively few studies performed in Third World countries which have examined the seasonal variation in food intake and the physiological adaptations made by those subjected to them; and gaps still remain in our knowledge of the energy and nutrient needs for these populations. Most of the studies that have been carried out involve the male population, or, if the female population is included, then more often than not the researchers examined only the effects of restricted energy intake on pregnancy and lactation. Hopefully, therefore, this study will give some insight into the situation for non-pregnant, non-lactating, hard-working women in southern India. The investigation was carried out in Edulabad, a village in the state of Andhra Pradesh, South India. A group of around 100 low-income female agricultural labourers were studied throughout two harvest and two lean seasons for changes in body composition by measuring their body weight, 5 skinfold thicknesses and 4 limb circumferences at 6 weekly intervals. A smaller group of 30 middle income housewives living in the same village were also measured at the same time as the working women, for comparison. These measurements were carried out in 1985 and repeated in 1986. Also in 1986, the variation of energy intake of 30 working women was measured in the harvert season, and the lean season. This was carried out using the individual weighted inventory method over a three day period, and the average of the three days intake was taken to represent the woman's daily intake for that season. The intake of 10 middle income housewives was also measured by the same method, for comparison. Using indirect calorimetry (Douglas Bag method) the basal metabolic rates of the same group of 30 working women were determined, again in the harvest and lean seasons. On the same days they performed a 3 level step test of increasing work intensity, to determine their aerobic capacity. Finally, the working women were followed for 3 days by a local observer who recorded their activities minute by minute. This was carried out twice, at the same time as the food intake measurements. The women's activities were divided into ten major categories: lying in bed; sitting activities; standing; standing activities; persona lneeds; housework; walking; manual work; field work. In summary the results showed that the working women in this study tended to lose weight after the harvest season when there was restricted food availability and when what was available was more expensive to buy ie they lost 0.5 kg - from 40.0 kg to 39.5 kg, and 0.4 kg - from 39.7 kg to 39.3 kg in 1985 and 1986 respectively. These working women fell below the FAO/WHO/UNU 1985 recommendations for desirable weight for height and body mass index. There was a small fall in total skinfold thicknesses from the harvest to the lean season, 1985. Similarly in 1986 where there was a bigger reduction in total skinfold thicknesses, from 43.3 mm to 40.8 mm in the harvest and lean season respectively. This was reflected in a significant drop in percentage body fat in 1986, from 21.4 to 20.1 per cent. These values obviously represent a population with very little body fat. Limb circumferences were reduced significantly in 1985 in the buttocks thigh and calf measurements, and also tended to decrease in 1986, but failed to reach significance. There were no significant differences between the sets of measurement on the middle income 'control' women between the seasons. This absence of difference may indicate that a greater reliability can be placed on the data for the working women which do exhibit seasonal changes. The middle income women were found to be 10 kg heavier than the working women, with a higher percentage body fat - around 30%. These women did fall into the FAO/WHO/UNU desirable ranges for weight for height, and BMI. There was found to be a significant difference in energy intake in the working women between seasons - 2030 Kcal/day in the harvest season and 1890 Kcal/day in the lean season. Therefore a situation seems to exist where food availability is decreased as an effect of the seasons. The middle income women had an intake much less that the working women, of 1760 Kcal/day, which would be expected since they were not involved in any manual labour. Comparing these results with the relative energy requirements of women of similar age and weight as given by FAO/WHO/UNU 1985, the middle income women fall into the low end of the range in level of activity, whereas the working women are classified as involved in "very heavy" activity. (Abstract shortened by ProQuest.)