An Overview of Refeeding Syndrome

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Refeeding syndrome is a potentially life-threatening complication that can occur when someone who is malnourished is refed and rehydrated. If a person is given nutrition and hydration too quickly, it can cause dangerous imbalances in electrolyte levels. When these changes are sudden, it can lead to problems with the heart, kidneys, and brain, which can be fatal.

Refeeding syndrome symptoms
Verywell / Gary Ferster 


The signs and symptoms of refeeding syndrome can come on suddenly and have devastating and potentially fatal consequences. When a person has been malnourished, even for a relatively short period of time, the body has many mechanisms that allow it to overcompensate. For this reason, people who are malnourished may initially have normal or near-normal lab test results.

When a person who is malnourished begins receiving nutrition and hydration, complications usually occur within the first few days. In a malnourished state, the body has become used to having to overcompensate. When a person starts eating and drinking again, especially more than they have been taking in for a long time, the body easily becomes overwhelmed.

Signs and symptoms of refeeding syndrome that may show up on tests include:

  • Abnormal sodium levels (hyponatremia)
  • Low potassium (hypokalemia)
  • Low phosphate (hypophosphatemia)
  • Low magnesium (hypomagnesemia)
  • Elevated blood sugar (hyperglycemia)
  • Increased heart rate
  • Low blood pressure
  • Anemia
  • Abnormal liver function
  • Abnormal urine tests or kidney function tests
  • Heart arrhythmias
  • Rapid weight gain (from fluid retention)
  • Vitamin deficiencies and other metabolic changes

A person with refeeding syndrome may also experience fatigue, weakness, breathing difficulty, abdominal pain, nausea, and vomiting. In addition, they may have bowel changes, swelling, muscle pain, paralysis, confusion, seizures, and is at risk of becoming comatose.

If not recognized and promptly treated, refeeding syndrome can be fatal.


Refeeding syndrome has been observed for decades in people who are starving as the result of capture (such as prisoners of war or people who were in concentration camps), famine, poverty, or illness. When medical professionals encountered severely malnourished people in the past, the assumption was that these starving individuals should be allowed to eat and drink normally—or even take in large quantities of nourishment—to address their prolonged hunger and begin to heal their bodies.

Doctors were startled when, after being allowed to eat and drink freely, many malnourished patients died rather than got better—sometimes within just a few days of beginning to eat and drink again.

While it seemed counterintuitive, the medical staff realized that instead of immediately letting the starving individuals return to normal patterns of eating and drinking, they needed to slowly refeed and rehydrate them over time to avoid overwhelming their compromised systems. During this period of refeeding, these patients also needed constant monitoring—as some potential metabolic changes (such as low potassium levels) that could be fatal often occurred suddenly.

What Happens to the Body

When the body does not get adequate nutrition and hydration, it is forced to break down fat stores, and eventually muscle, for energy. The longer a person is in a state of starvation, the more the body will use these stores. If a person is not eating and drinking enough, the stores are not being replenished.

As a person becomes more malnourished, the body is less able to handle the demands of normal living and activity. Muscle wasting and loss of fat stores don't just affect a person's ability to move around—it also weakens their vital organs. The most vulnerable muscle in the body is the heart, which is why people who are malnourished can develop heart problems.

As malnourishment progresses, a person will also become more vulnerable to injury and illness. The immune system becomes impaired when the body is starving, so a person will not be able to heal from illness or injury very well.

Poor healing makes it more likely a person will get very sick or develop long-term health problems.

Refeeding syndrome can occur in any malnourished person, but most often occurs in people who have been hospitalized. There are some conditions or risk factors that make it more likely a person will experience the complication.

You are most at risk for refeeding syndrome if you have any of these risk factors:

  • You have had little or nothing to eat for 10 or more days in a row.
  • Your body mass index (BMI) is less than 16.
  • Your blood tests show low levels of phosphate, potassium, sodium, or magnesium.
  • You have recently lost a lot of weight (15% of your normal body weight or more over the last three to six months).

You are also more likely to experience refeeding syndrome if you have at least two of the following risk factors:

  • You've lost 10% or more of your normal body weight in the last three to six months.
  • Your BMI is under 18.
  • You have not eaten for five days in a row.
  • You have been diagnosed with an eating disorder, including anorexia or bulimia nervosa.
  • You use alcohol.
  • You are recovering from surgery.
  • You are having a hard time controlling your diabetes.
  • You are receiving chemotherapy.
  • You take medications that alter certain minerals, vitamins, and fluid levels in your body such as diuretics (also called water pills), insulin, or antacids.

It's important to remember that a person can be at a normal weight—or even overweight—and still be suffering from poor nutrition.

You may be at risk for refeeding syndrome if you are in a malnourished state for any reason, including the inability to take food by mouth due to an injury or condition (for example, due to dental problems or surgery), you have a condition or injury affecting your ability to swallow, you have a gastrointestinal disease that makes it harder for your body to digest the food you eat (malabsorption), or have had weight-loss surgery.

In other cases, you may be at risk if your socioeconomic circumstances—including poverty, disability, and/or if you are elderly—are making it hard for you to regularly access nutritious food, if you do not have enough to eat, or if you are unable to purchase groceries.


Refeeding syndrome most often occurs in malnourished adults who have been hospitalized. It can occur in children, but this is less common. While medical professionals know that refeeding syndrome can occur, there is limited research on the problem. Doctors who regularly work with patients who are in the hospital because they are malnourished, such as oncologists or doctors working in eating disorder treatment centers, are most likely to encounter refeeding syndrome.

Close Monitoring

Even when medical professionals know that a person is at risk for refeeding syndrome, it can still be difficult to prevent it. The complication can develop quickly, so close monitoring of a person's vital signs (such as blood pressure and breathing) as well as frequent blood tests to check electrolyte levels is essential for their safety.

Monitoring of blood chemistry is important, because potentially life-threatening electrolyte imbalances may show up before a person starts showing other signs (such as confusion or weakness). For patients who have several risk factors, it's important that the entire medical team is aware of the possibility of refeeding syndrome and has been educated on its signs and symptoms.

If you are severely malnourished, you will likely be admitted to the hospital to begin the refeeding and rehydration process.

This way, your doctors can use tests to closely monitor you for signs of refeeding syndrome. Some of these tests may need to be run more than once. You may need to wear monitors or be hooked up to machines that will monitor your vital signs constantly while you are in the hospital and notify your medical team if any changes occur.

Medical Tests

The medical team caring for you will use several types of tests to monitor for signs of refeeding syndrome. This may include checking your pulse and blood pressure, asking you questions about how you feel and if you are in pain, as well as taking blood samples to check the levels of glucose, sodium, potassium, and other electrolytes.

In addition, your medical team will keep track of how much nutrition and fluid you take in (intake) and how much you excrete (output), take your temperature, weigh you or take measurements to assess your body mass, and care for any ports or IVs you have, especially if you are receiving fluids and nutrition through a tube (enteral or parenteral nutrition).


When refeeding syndrome occurs, the medical team will need to take prompt action to correct the life-threatening imbalances. Once a malnourished person's health is more stable, the plan of care will need to be changed to prevent further complications.

When a person is being refed and rehydrated after a period of malnutrition, it's important that the process is slow and deliberate, allowing the body enough time to adjust. If a person is going to need tube feeding, doctors usually will try to ensure they are well-hydrated and don't have any electrolyte imbalances. They may also be given some vitamin supplementation to correct any deficiencies (especially a thiamin deficiency).

Each person will need to be carefully evaluated by a team of doctors to determine their nutritional needs. Their fluid needs will differ and be assessed separately.

In general, the safest rate of refeeding for severely malnourished patients who are in the hospital is starting at about half of what their goal caloric intake will be, and gradually increasing how many calories they eat.

Depending on the underlying cause a person's malnutrition, other intervention may be needed. For example, a person with cancer may need concurrent treatment with chemotherapy and radiation, people with diabetes may need educating about monitoring their insulin, and people with eating disorders often work with mental health professionals as part of their recovery.

If doctors aren't sure what is causing a person's malnutrition, or if they have repeated bouts of malnutrition that are difficult to treat, additional medical investigation will be needed to determine the best course of treatment and prevent any potential serious, long-term complications.

Once patients have been treated for malnutrition, maintaining weight and nutrition after refeeding usually requires a team of doctors and allied health professionals. Dietitians and nutrition specialists can help people ensure they are eating a balanced diet as well as eating enough to meet their body's energy needs. They may need to see their primary care doctor or a specialist regularly to monitor their weight and body mass, as well as address any ongoing vitamin deficiencies.

A Word From Verywell

Refeeding syndrome is a potentially life-threatening condition that can occur when a person who is severely malnourished begins to eat and drink again. Electrolyte imbalances can affect the heart, brain, and other major organs and lead to serious complications which can be fatal. Adhering to slow and steady rehydration and calorie restoration protocol is essential to a person's safety and wellbeing. Long-term follow-up care for people who have been treated for malnutrition will need to include many different healthcare professionals depending on the underlying cause, including mental health professionals, specialists, and registered dieticians.

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