A model of seasonal changes in energy balance

Abstract

In developing countries, many peasant farmers experience regular seasonal changes of body weight, so that the adequacy of food energy supply cannnot be assessed simply in terms of energy balance and a desirable body weight. A computer simulation model has been devised, which predicts the pattern of changes in body weight which result from the annual cycle of agricultural work load, and the way in which food consumption is regulated over the year. The model also includes the effect of post‐harvest storage losses. The actual observed patterns of food use of farmers in The Gambia, and in Burma, are first of all used to simulate the seasonal changes in body weight and these agree well with observations. The effects of alternative strategies of food use are then tried, ranging from a constant intake throughout the year, to an exaggerated feasting and fasting cycle. The simulations show that the actual food allocation patterns adopted by these two peasant populations constitute an optimum strategy in which the need to achieve maximum body weight at the time when peak work output is required, is balanced against the need to minimise the losses due to long term food storage.