5. Conclusions

1. Seasonality in energy metabolism exists. However, it is not universal. It occurs especially, but not exclusively, in rural environments characterized, mostly but not necessarily, by marked climatic and agricultural fluctuations.

2. The overlap and interaction of several seasonal events confound the picture and may precipitate a marginal situation into imbalance in areas with low seasonality index.

3. Children appear to be affected as much as adults. Food shortage and contagious diseases are likely to be the main reasons, which distinguishes their situation from that of adults. The picture is further complicated by the fact that seasonal fluctuations of food availability and infectious diseases are tightly interlocked.

4. Seasonality of energy balance appears to cause a modest fluctuation of 2 to 5% of the body weight of adults, equivalent to the mobilization and subsequent redeposit of about 15,000 to 20,000 kcal of the body's energy stores. The evidence that adaptive mechanisms become operative in response to a seasonally negative energy balance of this size is scarce and contradictory.

5. Peaking of workloads appears to be closely associated with seasonal losses of body weight. This suggests that energy expenditure may be the critical factor in the causation of energy imbalance in adults. The preharvest food shortage may, but does not necessarily, contribute to energy imbalance.