Refeeding is the process of reintroducing food after malnourishment or starvation. Refeeding syndrome is a serious and potentially fatal condition that can occur during refeeding. It’s caused by sudden shifts in the electrolytes that help your body metabolize food.

The incidence of refeeding syndrome is difficult to determine, as there isn’t a standard definition. Refeeding syndrome can affect anyone. However, it typically follows a period of:

Certain conditions may increase your risk for this condition, including:

Certain surgeries may also increase your risk.

Food deprivation changes the way your body metabolizes nutrients. For example, insulin is a hormone that breaks down glucose (sugar) from carbohydrates. When carbohydrate consumption is significantly reduced, insulin secretion slows.

In the absence of carbohydrates, the body turns to stored fats and proteins as sources of energy. Over time, this change can deplete electrolyte stores. Phosphate, an electrolyte that helps your cells convert glucose into energy, is often affected.

When food is reintroduced, there’s an abrupt shift from fat metabolism back to carbohydrate metabolism. This causes insulin secretion to increase.

Cells need electrolytes like phosphate to convert glucose to energy, but phosphate is in short supply. This leads to another condition called hypophosphatemia (low phosphate).

Hypophosphatemia is a common feature of refeeding syndrome. Other metabolic changes can also occur. These include:

  • abnormal sodium and fluid levels
  • changes in fat, glucose, or protein metabolism
  • thiamine deficiency
  • hypomagnesemia (low magnesium)
  • hypokalemia (low potassium)

Refeeding syndrome can cause sudden and fatal complications. Symptoms of refeeding syndrome may include:

These symptoms typically appear within 4 days of the start of the refeeding process. Though some people who are at risk don’t develop symptoms, there’s no way to know who will develop symptoms before beginning treatment. As a result, prevention is critical.

There are clear risk factors for refeeding syndrome. You may be at risk if one or more of the following statements apply to you:

  • You have a body mass index (BMI) under 16.
  • You’ve lost more than 15 percent of your body weight in the past 3 to 6 months.
  • You’ve consumed little to no food, or well below the calories needed to sustain normal processes in the body, for the past 10 or more consecutive days.
  • A blood test has revealed your serum phosphate, potassium, or magnesium levels are low.

You may also be at risk if two or more of the following statements apply to you:

  • You have a BMI under 18.5.
  • You’ve lost more than 10 percent of your body weight in the past 3 to 6 months.
  • You’ve taken in little to no food for the past 5 or more consecutive days.
  • You have a history of alcohol use disorder or use of certain medications, such as insulin, chemotherapy drugs, diuretics, or antacids.

If you fit these criteria, you should seek emergency medical care immediately.

Other factors can also put you at an increased risk of developing refeeding syndrome. You might be at risk if you:

  • have anorexia nervosa
  • have chronic alcohol use disorder
  • have cancer
  • have uncontrolled diabetes
  • are malnourished
  • recently had surgery
  • have a history of using antacids or diuretics

Refeeding syndrome is a serious condition. Complications that require immediate intervention can appear suddenly. As a result, people at risk require medical supervision at a hospital or specialized facility. A team with experience in gastroenterology and dietetics should oversee treatment.

Research is still needed to determine the best way to treat refeeding syndrome. Treatment usually involves replacing essential electrolytes and slowing down the refeeding process.

The repletion of calories should be slow and is typically at about 20 calories per kilogram of body weight on average, or around 1,000 calories per day initially.

Electrolyte levels are monitored with frequent blood tests. Intravenous (IV) infusions based on body weight are often used to replace electrolytes. But this treatment may not be suitable for people with:

In addition, fluids are reintroduced at a slower rate. Sodium (salt) replacement may also be carefully monitored. People who are at risk of heart-related complications may require heart monitoring.

Recovering from refeeding syndrome depends on the severity of malnourishment before food was reintroduced. Refeeding may take up to 10 days, with monitoring afterward.

In addition, refeeding often occurs alongside other serious conditions that typically require simultaneous treatment.

Prevention is critical in avoiding the life-threatening complications of refeeding syndrome.

The underlying health conditions that increase the risk of refeeding syndrome aren’t always preventable. Healthcare professionals can prevent complications of refeeding syndrome by:

  • identifying individuals who are at risk
  • adapting refeeding programs accordingly
  • monitoring treatment

Refeeding syndrome appears when food is introduced too quickly after a period of malnourishment. Shifts in electrolyte levels can cause serious complications, including seizures, heart failure, and comas. In some cases, refeeding syndrome can be fatal.

People who are malnourished are at risk. Certain conditions, such as anorexia nervosa or chronic alcohol use disorder, can increase risk.

Complications of refeeding syndrome can be prevented by electrolyte infusions and a slower refeeding regimen. When individuals who are at risk are identified early, treatments are likely to succeed.

Increasing awareness and using screening programs to identify those at risk of developing refeeding syndrome are the next steps in improving the outlook.