Refeeding edema is due to increased release of-

Refeeding syndrome In severely malnourished individuals, attempts at rapid correction of malnutrition switch the body from a reliance on fat to carbohydrate metabolism. Release of insulin is triggered, shifting potassium, phosphate and magnesium into cells (with water following the osmotic gradient) and causing potentially fatal shifts of fluids and electrolytes from the extracellular to the intracellular compament. Rapid depletion of (already low) thiamin exacerbates the condition. Clinical features include nausea, vomiting, muscle weakness, seizures, respiratory depression, cardiac arrest and sudden death. The risks of refeeding are greatest in those who are most malnourished (especially chronic alcoholics), but even those who have gone without food for 5 days can be at risk and restitution of feeding should always be done slowly, with careful monitoring of serum potassium, phosphate and magnesium in the first 3-5 days. Ref - davidsons 23e p706