Effect on Metabolism

Depletion of food stores in the body tissues during starvation :
· Carbohydrate can supply the energy required for body functions for perhaps half a day.
· Except for the first few hours of starvation, the major effect are progressive depletion of tissue fat and protein.
o Fat is the prime source of energy
· The rate of the fat depletion continues unabated until most of the fat stores in the body are gone.
· Protein undergoes 3 phases of depletion:
o rapid depletion at first
§ Use of easily mobilized protein for direct metabolism or for convertion of glucose (metabolism of glucose mainly in the brain)
o then greatly slowed depletion
§ Remaining protein is not so easily removed
§ Rate of gluconeogenesis ↓ to to its previous rate
§ Lessened availability of glucose initiates a series of event that leads to excessive fat utilization and convertion of some of the fat breakdown products to ketone bodies(can be used by the brain cells for energy)
o finally rapid depletion again shortly before death(Protein is essential for the maintenance of cellular function)
§ Fat stores are almost depleted