Refeeding Syndrome

The Refeeding Syndrome is a bit like a man lost in a desert and when he finally reaches safety and water, he will drink too much in one go. Bedouins will tell you that you should drink with care. They're right, because too much too quickly can dilute the concentration of sodium in the blood, a condition called hyponatremia. When this happens, the balance of sodium in the fluids outside your body's cells is disrupted, fluid moves into the cells in an attempt to fix the imbalance and your cells swell. Brains cells are particularly prone to swelling. Symptoms of hyponatremia include confusion, convulsions, fatigue, loss of appetite, irritability and even death.

Refeeding is the equivalent of finding an oasis after prolonged fasting. Prolonged fasting occurs as a result of following idiotic diets, hunger strikes or religious fasting. Mostly, however, one finds the refeeding syndrome in severely malnourished patients in hospitals. When you are restricting your food intake over a prolonged period of time you essentially starve yourself. The body quickly switches from using carbohydrate to using fat and protein as the main source of energy. Not only metabolic changes occur but also hormonal changes. The net result of all this is that the metabolic rate decreases by as much as 20-25%.

These hormonal and metabolic changes are aimed at preventing protein and muscle breakdown. Muscle and other tissues decrease their use of ketone bodies and use fatty acids as the main energy source. This results in an increase in blood levels of ketone bodies, stimulating the brain to switch from glucose to ketone bodies as its main energy source. The liver decreases its rate of gluconeogenesis, thus preserving muscle protein.

So, what happens if you stop fasting and start eating again. Some potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving (artificial) refeeding[1]. These shifts result from hormonal and metabolic changes and may cause serious clinical complications. The hallmark biochemical feature of refeeding syndrome is hypophosphataemia or extremely low levels of phosphate in the blood. However, the syndrome is complex and may also feature abnormal sodium and fluid balance; changes in glucose, protein, and fat metabolism; thiamine deficiency; hypokalaemia; and hypomagnesaemia.

The true incidence of refeeding syndrome is unknown—partly owing to the lack of a universally accepted definition and research[2]. In a study of 10,197 hospitalised patients the incidence of severe hypophosphataemia was 0.43%, with malnutrition being one of the strongest risk factors.

[1] Mehanna et al: Refeeding syndrome: what it is, and how to prevent and treat it in British Medical Journal – 2008. See here.
[2] Camp, Allon: Severe hypophosphatemia in hospitalised patients in Mineral & Electrolyte Metabolism – 1990