Refeeding syndrome: what it is, and how to prevent and treat it

Summary

Refeeding syndrome describes the metabolic and clinical disturbances that occur when severely malnourished or starved patients are fed too aggressively. The mechanism: during prolonged fasting or starvation the body shifts from carbohydrate to fat and protein metabolism, insulin secretion drops, and intracellular minerals — particularly phosphate, potassium, and magnesium — become depleted even when serum levels appear normal. When carbohydrate intake resumes, insulin surges, and glucose, water, and these intracellular minerals shift rapidly back into cells. Serum phosphate, potassium, and magnesium can fall sharply within 24 to 72 hours of refeeding. Thiamine, a cofactor for carbohydrate metabolism, can also become acutely deficient. The combined picture — hypophosphataemia, hypokalaemia, hypomagnesaemia, fluid overload, thiamine deficiency — can precipitate cardiac arrhythmias, congestive heart failure, respiratory failure, seizures, rhabdomyolysis, haemolysis, and sudden death.

The review identifies major risk factors: BMI under 16, unintentional weight loss greater than 15 percent in three to six months, little or no nutritional intake for more than ten days, or low pre-feeding levels of phosphate, potassium, or magnesium. Minor risk factors that compound: BMI under 18.5, weight loss greater than 10 percent in three to six months, little or no intake for more than five days, or a history of alcohol misuse, chemotherapy, insulin, antacids, or diuretics. The authors endorse the National Institute for Health and Care Excellence (NICE) approach: in at-risk patients, begin feeding at a maximum of 10 kcal/kg/day (5 kcal/kg/day in extreme cases) and increase slowly over four to seven days; supplement thiamine and a B-vitamin complex before and during the first ten days of feeding; correct and monitor electrolytes daily; restore circulating volume cautiously; and replace phosphate, potassium, and magnesium as needed before and during the early refeeding period.

The take-home is straightforward: refeeding syndrome is preventable, but it requires that clinicians recognise risk before reintroducing nutrition and feed slowly with electrolyte and thiamine support, not rush calories into a depleted system.