Starvation has several stages. Our bodies are fantastically well adapted to deal with less than adequate amounts of food. The strategy the body adopts for surviving is dependant on the rate of starvation. If the starvation is slow enough the body will deplete nearly all of the fatty tissues before breaking down the liver and muscle fiberes for energy. If the starvation is sudden (ie no food at all) the body simultaneously breaks down the fat and the muscle/liver tissues after about a week.

When food is limited the body slows down requiring less food. After you enter stage one you lose your appetite (possibly a measure to make searching for food easier as the hunger pains are extremely distracting) Once in stage 3 it is unlikely that the person will recover even if given food, the body is not strong enough to break down the food to recover the energy from it to live.

Metabolic Stages of Starvation

Stage 1 Liver & muscle glycogenolysis
Stage 2 Gluconeogenesis (Liver & muscle glycogen stores depleted)
Stage 3 Terminal phase = Protein degradation (Lipid stores depleted)