Metabolic adaptation to malnutrition

Resting and nonresting energy expenditure are reduced in restricted volunteers. This decrease is due to fat-free mass depletion and also to a reduction in energy expenditure per kilogram of fat-free mass. Protein deprivation leads to a reduction in protein turn-over or oxidation in the postabsorptive state and to a decrease in the amplitude of diurnal cycling of protein turn-over, synthesis and breakdown. Such a metabolic adaptation tends to maintain fat mass and to reduce the need for essential amino acids. In adults with naturally occurring states of malnutrition, the results vary according to the cause of malnutrition. One may observe or not a reduction in energy expenditure or protein metabolism. The lack of reduction of metabolic adptation could be due to the long term energy and protein deprivation and to the preservation of visceral mass relative to muscle mass.