Refeeding Syndrome: An Overview

When a malnourished person is refed too quickly, it can be fatal

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, they can lead to problems with the heart, kidneys, and brain, which can be fatal.

Refeeding syndrome can also occur when someone who was extreme dieting or strictly fasting for a prolonged period of time suddenly begins to eat larger amounts.

This article discusses refeeding syndrome symptoms, causes, and complications. It also explains malnutrition treatment protocols to prevent refeeding syndrome.

Refeeding syndrome symptoms
Verywell / Gary Ferster 

What Is Refeeding Syndrome?

Refeeding syndrome is a complication of treatment for malnutrition. When a person is malnourished, the body overcompensates through various mechanisms to maintain homeostasis. This process means people with malnourishment often have normal or near-normal lab test results—especially in the early stages.

However, when a malnourished person begins receiving nutrition and hydration, the body can easily become overwhelmed. Refeeding syndrome can come on suddenly and have devastating consequences.

Accustomed to overcompensating for lacking nutrients, a sudden influx of hydration and nutrition can cause imbalances that can be fatal.

These include:

  • Abnormal liver function
  • Abnormal sodium levels (hyponatremia)
  • Abnormal urine tests or kidney function tests
  • Anemia
  • Elevated blood sugar (hyperglycemia)
  • Increased heart rate
  • Low magnesium (hypomagnesemia)
  • Low phosphate (hypophosphatemia)
  • Low potassium (hypokalemia)
  • Vitamin deficiencies and other metabolic changes

Refeeding Syndrome Symptoms

Symptoms of refeeding syndrome include:

  • Abdominal pain
  • Bowel changes
  • Confusion
  • Difficulty breathing
  • Fatigue
  • Heart arrhythmias
  • Increased heart rate
  • Low blood pressure
  • Muscle pain
  • Nausea
  • Rapid weight gain (from fluid retention)
  • Paralysis
  • Seizures
  • Swelling
  • Vomiting
  • Weakness

If not recognized and managed properly, refeeding syndrome can result in a coma or even death.


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.

Initially, healthcare providers allowed starving individuals to eat and drink normally to address their prolonged hunger and allow their bodies to heal. However, instead of returning to health, many malnourished patients died—sometimes within just a few days of beginning to eat and drink again.

While it seemed counterintuitive, medical professionals realized refeeding and rehydrating needed to occur slowly to avoid overwhelming their compromised systems. During refeeding, constant monitoring is needed. Some potentially fatal metabolic changes (such as low potassium levels) can occur suddenly.


Refeeding syndrome occurs in people who are malnourished, most commonly in those who have been hospitalized.

Other causes of malnutrition include an inability to take food by mouth due to an injury or condition such as dental problems or oral surgery, an inability to swallow, a gastrointestinal disease that impacts digestion (malabsorption), or weight-loss surgery.

In addition, socioeconomic factors—including poverty, disability, or old age—can impact access to nutritious food and lead to malnutrition.

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. Without food and water, these stores cannot be 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 weaken vital organs, most notably the heart. People who are malnourished can develop heart problems.

As malnutrition 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.

A person can suffer from malnutrition at any weight.

Risk Factors

Factors that put a person at the greatest risk for refeeding syndrome include:

  • 10 or more days in a row with little or nothing to eat
  • Blood tests show low levels of phosphate, potassium, sodium, or magnesium
  • A body mass index (BMI) of less than 16
  • Significant weight loss or 15% of your normal body weight or more over the last three to six months

People with two or more of the following are also at high risk for refeeding syndrome:

  • Difficulty controlling diabetes
  • An eating disorder, including anorexia, bulimia nervosa, or avoidant restrictive food intake disorder (ARFID)
  • A BMI under 18
  • Haven't eaten in five days in a row
  • Heavy alcohol intake
  • Lost 10% or more of normal body weight in the last three to six months.
  • Receiving chemotherapy
  • Recovering from surgery
  • Taking medications that alter certain minerals, vitamins, and fluid levels in your body such as diuretics (also called water pills), insulin, or antacids

Refeeding syndrome most often occurs in malnourished adults who have been hospitalized. It is less common in children but can occur.


People who are severely malnourished are typically admitted to the hospital to begin the refeeding and rehydration process. This allows for close monitoring of vital signs and bloodwork to quickly diagnose refeeding syndrome.

Bloodwork can often show potentially life-threatening complications before outward symptoms are evident. A healthcare team will closely monitor levels of glucose, sodium, potassium, and other electrolytes. Nutrition and fluid intake. urine output, weight, and body mass will also be tracked during refeeding.

Treatment and Prevention

Prompt action is needed to correct the life-threatening imbalances of refeeding syndrome. 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, healthcare providers 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 thiamine deficiency).

Each person will need to be carefully evaluated by a team of healthcare providers 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 of a person's malnutrition, other interventions may be needed. For example, a person with cancer may need concurrent treatment with chemotherapy and radiation, people with diabetes may need education about monitoring their insulin, and people with eating disorders often work with mental health professionals as part of their recovery.

Long Term Care

If healthcare providers aren't sure what is causing a person's malnutrition, or if they have repeated bouts of malnutrition that are difficult to treat, the 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 healthcare providers 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 healthcare provider 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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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Abby Norman
Abby Norman is a freelance science writer and medical editor. She is also the author of "Ask Me About My Uterus: A Quest to Make Doctors Believe in Women's Pain."