Chronic effects of over- and under-nutrition on thermogenesis

This paper reviews the evidence on the magnitude of the changes in energy expenditure during over- and underfeeding periods. It is of interest to know whether these changes can be explained by the predicted effects of the extra feed (or the missing feed) on dietary-induced thermogenesis (DIT) and the effects of changes in body composition and resting metabolic rate. Chronic overfeeding of both lean and obese subjects result in an increase in thermogenesis to a similar extent according to several studies. This increase is probably greater than it can be explained by a simple effect of DIT and the underlying mechanisms remain obscure. Underfeeding causes marked decrease in metabolic rate, and the lowering of thermogenesis is explained by the effect of prolonged underfeeding on body composition, particularly by the decrease in fat-free mass.