Total or partial starvation decrease both body fat mass and lean body mass. The latter comes along with a spectacular drop in intracellular glycogen and nucleotides phosphate, associated with decreased intracellular fluid volume and total body potassium, magnesium and phosphate pools. Upon renutrition, the provision of carbohydrate and the ensuing hyperinsulinemia cause a swift reversal of cellular hypometabolism, and to a rapid transport of extracellular phosphate, potassium and magnesium into the cells. This is more specifically related administration of carbohydrate and a rapid rise in plasma insulin concentration, which is responsible for an immediate increase in cellular energy metabolism, inhibition of lipid oxidation and stimulation of glycogen synthesis. These phenomenons can be some times at the origin of set of acute hydro-electrolytic imbalances and cardiac and neural dysfunctions known as "the refeeding syndrome". Occurrence of this syndrome can be largely prevented by a slow, graded administration of energy and carbohydrate upon initiation of refeeding and by the systematic administration of potassium supplement. The initial phase of refeeding also requires a careful monitoring of blood phosphate and magnesium concentrations, with administration of exogenous supplements when required.