An Overview of Refeeding Syndrome

Refeeding syndrome commonly occurs when someone who is malnourished, possibly as the result of an eating disorder, begins to eat more regularly again.

Unfortunately, the condition can become quite serious. Complex metabolic processes that take place when someone starts eating more regularly can result in complications such as heart failure, respiratory failure, electrolyte imbalances, and even death.

That’s one reason why anyone undergoing the refeeding process should work with a team of medical professionals. With proper care and precaution, it is possible to prevent refeeding syndrome, and help severely malnourished patients become stronger and healthier again, and continue on the path to recovery.

What is Refeeding Syndrome?

Refeeding syndrome is a serious health condition that occurs when someone who has been malnourished or undergone prolonged fasting starts to eat again. It is characterized by a shift in the body’s metabolism and electrolyte balance.

During times of underfeeding, the body undergoes major changes. Deprived of nutrients, it will slow down the metabolic process, which breaks down food and turns it into energy, in order to conserve future energy stores. The body may even begin breaking down stored fat and muscle for energy, in absence of sufficient nutrition.

But once food starts being reintroduced, the body must adjust once again. This can be an uncomfortable and possibly even dangerous process, especially if food is reintroduced too rapidly. It also often sets off an internal chain of reactions, which can have a number of consequences.

Changes in Electrolyte Levels

Electrolytes are a group of essential minerals, which help maintain a number of vital functions in the body. Electrolyte imbalance can lead to a number of complications.

With refeeding syndrome, common electrolyte imbalances that occur include low phosphate, potassium, and magnesium levels. These minerals all have different roles in the body, but many of them work to help power the body’s electrical impulses.

The charges set off by these electrolytes power key processes in the brain and nervous system and help move the muscles themselves, including the heart. Imbalances can lead to heart arrhythmias, muscle weakness, and seizures, among other health risks.

Fluid Imbalance

Electrolytes also play an important role in maintaining the body’s internal fluid levels. And when these are out of proportion, it can lead to a number of issues.

When someone begins refeeding after long periods of underfeeding, their body shifts into anabolism, or, essentially, the revving up of metabolism. This process requires more fluids to shift into the cells, which could lead to an imbalance in fluid levels.

Swelling and edema, which is a particular type of swelling, can happen as a result. [1]

Changes in Acid-Base Balance

In order to function most efficiently, the body requires a certain pH level. And a number of internal processes regularly take place to help balance acidic and alkaline compounds for optimum functioning.

When the body begins to process more glucose, nutrients, and other food parts during the refeeding process, it leads to a number of internal shifts, including not just in metabolism, but in insulin production and thyroid levels.

These changes can also lead to a shift in the acid-base balance within the body. Consequences of this instability include respiratory problems, and metabolic acidosis, in which the body has too much acid and insufficient base. [2]

Signs and Symptoms of Refeeding Syndrome

Refeeding after a period of underfeeding or malnutrition should always be done with the guidance of a medical team, due to the serious complications that can occur.

Still, there are some signs and symptoms that can help with identifying patients who may be struggling with refeeding syndrome.

Fluid Retention

Thanks to its effect on electrolytes and other bodily processes, refeeding syndrome can cause fluid retention, leading to swelling, particularly in the legs and feet.

People struggling with the condition may experience difficulties moving around.


Low blood sugar (hypoglycemia) is another common symptom of refeeding syndrome.

As the body starts to process food again, it may not be able to produce enough insulin to regulate blood sugar levels, leading to low blood sugar. This can cause shakiness, sweating, confusion, and even seizures.

Respiratory Distress

Refeeding syndrome may cause respiratory distress, leading to shortness of breath and difficulty breathing. This is associated with the buildup of fluid in the lungs, which makes it difficult for the body to get enough oxygen.


Fatigue is a common symptom of refeeding syndrome, as the body works hard to adjust to the new influx of nutrients. It may take a while to build up enough energy to function properly.

Cardiac Issues

Refeeding syndrome can also cause cardiac issues like cardiac arrhythmias and heart failure in individuals with anorexia nervosa (AN). [3]

The electrolyte imbalances caused by refeeding syndrome can affect the heart’s ability to pump blood properly, leading to additional heart-related complications.

Short- and Long-Term Effects of Refeeding Syndrome

The sudden influx of nutrients into the body after periods of underfeeding can cause various short-term and long-term effects.

In the short term, refeeding syndrome can cause:

  • Muscle weakness
  • Cramps
  • Irregular heartbeat
  • Swelling
  • Fluid accumulation in the lungs and other organs

In the long term, refeeding syndrome can progress to cause damage to various organ systems. The heart, for example, may develop issues, leading to heart failure. The liver and pancreas may also become damaged, increasing the risk of infection and other complications.

Furthermore, refeeding can also lead to an increased risk of developing anemia, or a low count of red blood cells, which can come with its own spate of problems, such as fatigue, weakness, chest pain, or irregular heartbeat.

Who is At Risk of Developing Refeeding Syndrome?

Refeeding syndrome particularly affects people who have experienced long bouts of underfeeding or malnourishment. This can come about for a number of people, including:

  • Individuals with anorexia nervosa. This mental health condition is characterized by an intense fear of gaining weight, resulting in a severely restrictive diet, and often leading to underfeeding. Refeeding syndrome is considered a particularly large risk for people struggling with AN.
  • Individuals with other eating disordersBulimia nervosa (BN), avoidant/restrictive food intake disorder (ARFID), and other eating disorders that involve restrictive eating patterns can also put an individual at risk for the kind of malnourishment that would trigger refeeding syndrome.
  • Individuals who practice long-term fasting. The act of not eating or partaking in a very low-calorie diet for an extended period may put someone at risk for refeeding syndrome, if/when they start eating more again.
  • Individuals with a history of alcohol abuseAlcoholism can lead to malnutrition, which is tied to an increased risk of developing refeeding syndrome.
  • Individuals who have had gastrointestinal surgery. Gastrointestinal surgery can disrupt the normal absorption of nutrients, leading to malnutrition, and, eventually, refeeding syndrome.
  • Individuals with a chronic illness. Cancer, AIDS, chronic obstructive pulmonary disease (COPD), and other illnesses that work to decrease appetite or make it difficult to eat can lead to underfeeding, malnutrition, and an increased risk of refeeding syndrome.
  • Individuals who have had a recent illness or injury. Any illness or injury that results in a loss of appetite or decreased food intake can put an individual at risk for refeeding syndrome.
  • Patients with chronic malnutrition. This can be caused by a number of health concerns, including marasmus, morbid obesity with profound weight loss, malabsorptive syndrome, inflammatory bowel disease, cystic fibrosis, and short bowel syndrome.

How to Diagnose and Treat Refeeding Syndrome

To diagnose refeeding syndrome, healthcare professionals will study an individual’s medical history, including information about their eating habits. Additionally, it is important to consider any underlying conditions a patient may have which could contribute to the development of the complication.

Doctors may perform physical exams and other diagnostic tests to check for signs of electrolyte or fluid imbalances. A hospital’s dietetics team can also be involved, to look for levels of specific nutrients and minerals, and ensure that the appropriate nutritional interventions are implemented.

Early detection of refeeding syndrome is crucial to prevent further complications. If identified, it is important to slow down the feeding rate and replenish essential electrolytes to stabilize the patient’s condition.

Treating Refeeding Syndrome

Treatment for refeeding syndrome involves addressing any underlying nutritional imbalances that are causing further complications. This may include supplementing the diet with potassium, phosphorus, and magnesium. Fluids may also be given to help correct any fluid imbalances.

As someone’s body will continue to change and adapt as they add more calories and nutrients to their daily intake, it is essential for a medical team to continue monitoring a patient’s progress, and adjust any treatments as needed. The patient should also have a balanced diet that provides enough calories and nutrients to support healing and recovery.

An influx of food after periods of undereating can feel uncomfortable, and set off any number of internal reactions, but with professional help, it can be possible to avoid refeeding syndrome, and work toward managing the condition and improving overall health.

How to Reduce the Risk of Developing Refeeding Syndrome

Following a gradual and controlled refeeding plan is important to reduce the risk of refeeding syndrome. Working with a medical team is the best way to ensure this plan is monitored and adjusted as needed, to avoid any potential health risks.

Assess the Individual’s Nutritional Status

Before starting any refeeding plan, it’s important to assess someone’s current nutritional status. This will give doctors a baseline to start off of, and help them understand the internal mechanisms that may already be starting up.

It’s not uncommon for a medical team to measure someone’s body weight and height, and order blood tests to assess internal measurements, such as electrolyte, glucose, and other nutrient levels.

Start with a Low-Calorie Diet

While there is some scientific debate about the best way to initiate a refeeding schedule, many agree that a refeeding plan should start with a low-calorie diet.

An early emphasis is on providing essential nutrients such as protein, vitamins, and minerals. This may mean providing a diet that’s high in fruits, vegetables, and lean protein sources, such as fish.

Monitor Electrolyte Levels

Electrolyte imbalances, particularly low potassium, magnesium, and phosphorus levels, are a common complication of refeeding syndrome. It’s important to monitor electrolyte levels closely throughout the refeeding process.

If a doctor, nutritionist, or other member of the medical team notices levels beginning to change, they should keep a close watch on this progress, and adjust any refeeding diets accordingly.

Therapy support

Provide Psychological Support

Undernutrition is often associated with poor access to food and poverty, while the type of underfeeding and malnutrition associated with eating disorders is commonly linked to other mental health conditions.

Providing psychological support for someone undergoing refeeding can help address these underlying issues, which can work to improve their overall sense of well-being, and their chances of sustained recovery.

Finding Help for an Eating Disorder

If you or a loved one are struggling with undernutrition due to an eating disorder, it’s a good idea to seek help.

You can start by speaking with your physician, or with a mental health therapist. These medical professionals may be able to point you in the direction of more information, better resources, and the type of programs that can help.

If you are experiencing undernutrition for any reason, it is important to seek medical help. Attempting to regain weight on your own can lead to dangerous imbalances in the body, which could cause a number of serious complications.

Still, the important thing to remember is that help is always available. With the right kind of guidance and support, it is possible to safely regain nutrition and embark on the road to recovery.


  1. Shrimanker, I., Bhattarai, S. (2022). Electrolytes. StatPearls. Retrieved January 25, 2023.
  2. Singla, M., Perry, A., & Lavery, E. (2012). Refeeding syndrome as an unusual cause of anion gap metabolic acidosisMilitary medicine; 177(11):1393–1395.
  3. Kohn, M. R., Golden, N. H., & Shenker, I. R. (1998). Cardiac arrest and delirium: presentations of the refeeding syndrome in severely malnourished adolescents with anorexia nervosaThe Journal of Adolescent Health; 22(3):239–243.

The opinions and views of our guest contributors are shared to provide a broad perspective of eating disorders. These are not necessarily the views of Eating Disorder Hope, but an effort to offer discussion of various issues by different concerned individuals.

We at Eating Disorder Hope understand that eating disorders result from a combination of environmental and genetic factors. If you or a loved one are suffering from an eating disorder, please know that there is hope for you, and seek immediate professional help.

Last Updated & Reviewed By: Jacquelyn Ekern, MS, LPC on February 22, 2023
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