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Refeeding Syndrome and Anorexia

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Refeeding Syndrome and Anorexia

What is Refeeding Syndrome? 

Refeeding syndrome is a constellation of symptoms that can occur when an individual has been starving or malnourished for a long time and then too quickly re-introduces calories and a regular diet. When nutrition is introduced too quickly to someone who has been chronically malnourished, as is often the case with severe anorexia nervosa (AN), it can cause hormonal and metabolic changes that become serious and even life threatening. Individuals with severe malnourishment as a result of AN should be closely monitored as they begin treatment in order to prevent refeeding syndrome.

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Why Refeeding Syndrome Happens When Treating Anorexia

Adding too many nutrients too fast causes imbalances in water and electrolytes to individuals who are chronically malnourished.In addition, rapid repletion of fats and proteins can be hard for the body to process when it has become unaccustomed to doing so, leading to bloating, nausea, vomiting and diarrhea. (3)

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Risks of Refeeding

You might think that the patient with anorexia needs nutrition so that nutrition should be given quickly. However, rapid refeeding can lead to refeeding syndrome. (4)

Delirium can also be associated with the refeeding syndrome. Although it is rare, it can happen in low weight patients with anorexia. The delirium may occur because of the thiamine deficiency or the depletion of the electrolytes. However, most likely there are several factors coming together to cause the problem. Patients should be monitored during the refeeding process so this doesn’t happen and the situation can be rectified immediately. (5)

In one study that took place at 30 hospitals in France, doctors reviewed the charts of patients who had been treated for anorexia nervosa between May 2006 and May 2008. There were 68 patients including 62 women in the case reports. The average weight of the patients was 26.4 to 33 pounds. Many were put on a ventilator to help them breathe. The average caloric intake of these patients per day was 267 to 424 calories, which is about a quarter of the average woman’s daily caloric needs. refeeding during their treatment. Seven patients developed refeeding syndrome. Those who developed refeeding syndrome had double the number of calories as those who didn’t. Seven patients died; five from multi-organ failure associated with water and electrolyte imbalances, and two from respiratory distress. (6) 

In extreme cases, patients who are malnourished from anorexia nervosa may need to be hospitalized for the first few days to weeks of treatment in order to initiate nutrition and prevent complications of refeeding syndrome. The nutritional therapy given could be oral via food or parenteral supplementation (feeding through an intravenous line). Parenteral supplementation means administering nutrition therapy such as cans of Ensure somewhere in the body other than by mouth or a tube that goes into the stomach. When refeeding is done right, there is medical stabilization, nutrition rehabilitation, and weight restoration.

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How Do We Treat Anorexia Nervosa and Prevent Refeeding Syndrome?

Because refeeding syndrome is rare and hard to predict, there are no strict guidelines about exactly how to start refeeding a patient that is malnourished. At the Department of Clinical and Preventive Nutrition Sciences at Rutgers University in New Jersey, doctors published a study in the Nutrition and Clinical Practice journal in 2022. The study found that adequate supplementation and careful monitoring of certain nutrients - potassium, magnesium, thiamine - prevented severe refeeding syndrome However, all the approaches to giving these supplements were different and no one could come up with strict guidelines about exactly how to best supplement patients to avoid refeeding syndrome. (4)

In one review article about different approaches to refeeding in patients with anorexia, 12 studies published since 2010 had approaches that started out with more than 1400 calories per day. (2)

Here’s what they found with those studies:

  • In mildly and moderately malnourished patients, calories lower than 1400 per day is too conservative. 
  • Higher calorie levels can be given via meal or meals plus a nasogastric tube.
  • Giving higher caloric levels did not increase the risk for the refeeding syndrome when there was close medical monitoring with correction of the electrolytes as needed.
  • In severely malnourished patients, changing the protocols wouldn’t be based on any type of evidence from the studies.
  • Parenteral nutrition is not recommended.
  • Nutrient compositions within recommended ranges are appropriate.
  • More research is needed for those working with refeeding patients in non-hospital settings.
  • No one knows the long-term effects of different approaches.

The first thing that has to be established is what calorie level the patient needs to stimulate weight gain. This weight gain has to start happening at the beginning of treatment. It should then become more and more effective while minimizing the risk of refeeding syndrome. (1)

Refeeding syndrome can be best avoided by slow reintroduction of calories and vitamins, with frequent monitoring of electrolytes during the process. There is no consensus on exactly how to refer someone, and approaches need to be varied for the individual needs of the patient. However, if done with careful medical supervision and adequate support, refeeding can be done safely and can be an essential first step toward recovery from anorexia nervosa. Reach out to our team at Within Health to learn about our virtual care programs for anorexia nervosa.

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Frequently asked questions


  1.  Skowronska A, Sojita K, Strzelecki D. Refeeding syndrome as treatment complication of anorexia nervosa. Psychiatr Pol. 2019 Oct 30;53(5):1113-1123. 
  2. Garber AK, Sawyer SM, et al. A systematic review of approaches to refeeding in patients with anorexia nervosa. Int J Eat Disord. 2016 Mar;49(3): 293-310. 
  3. Castro MA, Martinez CV. The refeeding syndrome. Importance of phosphorus. Med Clin (Barc). 2018 Jun 22;150(12):472-478. 
  4. Gallagher D, Parker A, Samavat H, Zelig R. Prophylactic supplementation of phosphate, magnesium, and potassium for the prevention of refeeding syndrome in hospitalized individuals with anorexia nervosa. Nutr Clin Pract. 2022 Apr;37(2):328-343. 
  5. Norris ML, Pinhas L, Nadeau PO, Katzman DK. Delirium and refeeding syndrome in anorexia nervosa. Int J Eat Disord. 2012 Apr;45(3):439-42. 
  6. Vignaud M, Constantin JM, Ruivard M et al. Refeeding syndrome influences outcome of anorexia nervosa patients in intensive care unit: An observational study. Crit Care. 2010;14(5):R172.
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