Refeeding syndrome can develop when someone who is malnourished begins to eat again. The syndrome occurs because of the reintroduction of glucose, or sugar. As the body digests and metabolizes food again, this can cause sudden shifts in the balance of electrolytes and fluids. These shifts can cause severe complications, and the syndrome can be fatal.

It can take as few as 5 successive days of malnourishment for a person to be at risk of refeeding syndrome. The condition can be managed, and if doctors detect warning signs early, they may be able to prevent it.

Symptoms of the syndrome usually become apparent within several days of treatment for malnourishment.

What are the causes of refeeding syndrome?

patient being fed intravenously
Refeeding syndrome can occur when food is reintroduced to a person who is malnourished.

If a person does not eat enough, the body can quickly go into starvation mode and become malnourished.

After an extended period of starvation, the ability to process food is severely compromised.

A malnourished body produces less insulin, and this inhibits the production of carbohydrates.

If the body has insufficient carbohydrates, it uses fat reserves and stored proteins for energy.

If, over time, the body continues to rely on reserves of fat and protein, this can change the balance of electrolytes. Levels of vitamin and electrolytes diminish as the body tries to adapt to starvation mode. Potassium, phosphorus, magnesium, calcium, and thiamine levels are commonly affected.

When food is reintroduced, the body no longer has to rely on reserves of fat and protein to produce energy.

However, refeeding involves an abrupt shift in metabolism. This occurs with an increase in glucose, and the body responds by secreting more insulin. This can result in a lack of electrolytes, such as phosphorous.

Refeeding syndrome can cause hypophosphatemia, a condition characterized by a phosphorus deficiency. It can also lead to low levels of other important electrolytes.

The harmful effects of refeeding syndrome are widespread, and they can include problems with the:

  • heart
  • lungs
  • kidneys
  • blood
  • muscles
  • digestion
  • nervous system

If doctors are unable to treat the syndrome, it can be fatal.

Who is at risk?

Refeeding syndrome affects people who do not receive enough nutrition.

This may be because of:

  • starvation
  • malnourishment
  • extreme diets
  • fasting
  • famine

The following medical conditions can also increase the risk of developing refeeding syndrome:

Undergoing particular surgeries, especially weight loss surgeries, can also increase a person’s risk.


Electrolytes play an essential role in the body. When the balance is skewed, the most common complication is hypophosphatemia, which is a lack of phosphorus.

Symptoms of hypophosphatemia include:

  • confusion or hesitation
  • seizures
  • muscle breakdown
  • neuromuscular problems
  • acute heart failure

Refeeding syndrome can also lead to a lack of magnesium. Hypomagnesemia is the name for dangerously low levels of magnesium.

Signs and symptoms of hypomagnesemia include:

  • low calcium levels, or hypocalcemia
  • low potassium levels, or hypokalemia
  • weakness
  • fatigue
  • nausea and vomiting
  • abnormal heart rhythms

Refeeding syndrome can also cause potassium levels to drop dangerously low. This can lead to:

  • fatigue
  • weakness
  • excessive urination
  • breathing problems, such as respiratory depression
  • heart problems, such as cardiac arrest
  • ileus, which involves a blockage in the intestines
  • paralysis

Other symptoms include:

  • hyperglycemia, or high blood sugar
  • mental problems, such as confusion
  • abnormal serum sodium levels
  • fluid retention
  • muscle weakness

In some cases, a potassium deficiency can lead to a coma or death.

Doctors can identify people at risk for refeeding syndrome, but it is impossible to know whether a person will develop it. Attempting to prevent the syndrome from developing is vital.

Risk factors

bottle of alcohol on its side with man slumped on table
A history of alcohol use disorder can put a person at risk for refeeding syndrome.

People who have experienced recent starvation have the highest risk of developing refeeding syndrome.

The risk is high when a person has an extremely low body mass index.

People who have recently lost weight quickly, or who have had minimal or no food before starting the refeeding process are also at significant risk.

Other people at risk include:

  • children or adolescents with severely restricted calorie intakes, when this occurs with vomiting or laxative misuse
  • children or adolescents with a history of refeeding syndrome
  • frail individuals with multiple medical problems

Regardless of age, a person is at high risk if they have:

  • a BMI of less than 16
  • lost more than 15 percent of their body weight unintentionally in the past 3–6 months
  • consumed minimal food over the past 10 consecutive days or more
  • low levels of serum phosphate, potassium, or magnesium

Two or more of the following issues also increases the risk of developing refeeding syndrome:

  • a BMI of less than 18.5
  • unintentionally losing 10 percent of body weight in the past 3–6 months
  • consuming little or no food in the past 5 consecutive days or more
  • a history of alcoholism or drug abuse
  • receiving some treatments, such as insulin, diuretics, chemotherapy drugs, radiation therapy, and antacids

Anyone who suspects that they have refeeding syndrome should seek immediate medical care.

What are the treatment options?

People with refeeding syndrome need to regain normal levels of electrolytes. Doctors can achieve this by replacing electrolytes, usually intravenously.

Replacing vitamins, such as thiamine, can also help to treat certain symptoms. A person will need continued vitamin and electrolyte replacement until levels stabilize.

Doctors may also slow the refeeding process, to help a person to adjust and recover.

The person will require continual observation in a hospital. Doctors will monitor electrolyte levels and bodily functions with tests, including urine and blood analyses.


Recovery times vary, depending on the extent of illness and malnourishment.

Treatment will continue for up to 10 days, and monitoring may continue afterward.

If a person has complications or underlying medical problems, treatment for these may lead to longer recovery time.

Can it be prevented?

health professionals discussing patients diagnosis
It is important for healthcare professionals to look out for warning signs and treat at-risk patients.

Prevention is the most effective way to combat refeeding syndrome.

Healthcare professionals that are aware of warning signs and risk factors are better able to treat malnourished patients.

In 2013, researchers found that in a large sample of people being fed intravenously in the UK, 4 percent had refeeding syndrome. The authors noted that doctors only recognized the risk in half of the at-risk patients.

Healthcare professionals can prevent refeeding syndrome by:

  • quickly identifying those at risk
  • adapting refeeding programs
  • monitoring patients continuously once treatment has begun

Malnourishment can result when food intake is severely limited. This may occur in people with:

  • depression
  • dysphagia
  • alcoholism and drug use
  • anorexia nervosa
  • uncontrolled diabetes

Surgery and illnesses such as cancer can result in increased metabolic demands, leading to malnourishment.

Malnourishment can also occur when the body no longer absorbs nutrients as it should. This can result from conditions such as celiac disease and inflammatory bowel disease.

Patients at high risk of malnourishment and refeeding syndrome must be identified and treated. Guidelines state that doctors should consider a person’s alcohol intake, nutrition, weight changes, and psychological state before refeeding.


Refeeding syndrome can occur when food is reintroduced too quickly after a period of starvation or malnourishment. This can lead to electrolyte imbalances and severe complications that can be fatal.

The best way to combat refeeding syndrome is to identify and treat at-risk people. People with the syndrome can recover if they receive treatment early. Education and increased awareness of the condition can help.