Abstract:
The purpose of the study was to establish the existence of seasonal exposure to energy deficiency in rural areas of developing countries and to investigate the sequence of appearance and the nature of energy-sparing mechanisms utilized under real life conditions. The body weight of a group of 226 rural Ethiopian women was measured repeatedly over a one year period, at 45 day intervals. On a sub-group of 22 non-pregnant women total energy intake, TEI, total energy expenditure, TEE, and basal metabolic rate, BMR were also measured by the precise weighing method and by indirect calorimetry (Kofranyi-Michaelis respirometer or Douglas bag) and activity diaries. Body weight was found to have a moderate but statistically significant seasonal trend, with an overall loss of 1.6 kg. Women with higher BMI had larger seasonal swings of their body weight. Seasonal fluctuations were also found for TEI (maximum difference 420 kcal/d, not significant), and for BMR (maximum difference 200 kcal/day, P less than 0.000). TEE (mean yearly value of 1909 kcal/d, 42 kcal/kg) was very stable over the year and did not show any seasonal fluctuation. The present findings suggest that, under the study circumstances, seasonal exposure to fluctuation in food availability caused a moderate weight loss which was sufficient to induce metabolic adaptations, but not to cause any detectable change in physical activity.