Medical complications of eating disorders

Presented by Chrissy Stockert, Director of Health Services and Quality Assurance

Eating disorders are complex psychiatric and medical conditions that can cause devastating consequences on a person’s health, with some of the most severe complications being seizures, coma, heart failure, and even death. 

Why should we care about eating disorder complications?

Eating disorders are the most deadly mental health disorders. Individuals who have received inpatient treatment for anorexia have a 500% higher mortality risk than the general population. People with bulimia and those with anorexia treated on an outpatient basis have twice the mortality risk of controls.1

Worldwide, eating disorders are responsible for more than 3 million lost healthy years. And compared to other psychiatric conditions, bulimia and anorexia patients experience more years lived with disability.1

Contrary to misconceptions perpetuated by our society, eating disorders affect everyone, people of all ages, genders, sizes, races, ethnicities, religions, sexualities, abilities, classes, and beyond. 

Changes in bloodwork

Our blood is miraculous in that it is always working to maintain stability and balance, even throughout the course of an eating disorder. Many people with eating disorders may have normal bloodwork because of this, which means that when someone’s labs come back abnormal, this can be a sign of a significant issue that could very well result in dangerous consequences.

Electrolyte disturbances

Eating disorders are commonly associated with electrolyte disturbances, which can lead to many other problems. Two of the most common electrolyte issues are hyponatremia (low sodium levels) and hypokalemia (low potassium levels).1

Low sodium can cause many problems, such as:2

  • Headache
  • Confusion
  • Low energy
  • Drowsiness
  • Restlessness and irritability
  • Muscle cramps or weakness
  • Seizures
  • Coma

Hyponatremia is often a result of “water loading,” which occurs when a person with an eating disorder has kidneys that aren’t functioning correctly, causing them to retain considerable amounts of fluid. That extra water can cause sodium levels to plummet. 

Low potassium levels can be dangerous and well and lead to:2

  • Fatigue
  • Muscle weakness
  • Spasms
  • Tingling
  • Heart palpitations
  • Cardiac arrhythmia 

Hypokalemia is tied to purging behaviors, such as self-induced vomiting, laxative misuse, diet pill use, or diuretic use. Purging can remove potassium from the body, and it doesn’t happen over time—it can come on very quickly and be catastrophic.

Dangerously low glucose levels

Usually, when someone eats a meal, the nutrients are absorbed into the bloodstream and carried to the pancreas, which then releases insulin. Insulin helps the glucose travel from the bloodstream into the cells, where it can do its job of providing energy for cell functions. 

When someone has an eating disorder like anorexia, they may experience hypoglycemia (low blood sugar) due to food restriction, which can cause a host of symptoms, such as:3

  • Racing heart
  • Shaking
  • Sweating
  • Anxiety
  • Irritability
  • Dizziness
  • Headache

Complications of hypoglycemia can be life-threatening and may include:4

  • Loss of coordination
  • Slurred speech
  • Blurred vision
  • Unresponsiveness
  • Confusion
  • Seizure
  • Coma

In certain circumstances, people with eating disorder-related hypoglycemia may be asymptomatic, so they never realize it’s a problem. This is especially dangerous since the body isn’t telling the individual something is wrong. As a result, people can die very suddenly from asymptomatic hypoglycemia.

Phosphorus deficiency

Phosphorus is an essential component of ATP, which provides energy to our bodies’ cells and causes effective muscle contraction. Eating disorder behaviors like restricting, vomiting, exercising, and laxative abuse can cause phosphorus deficiency in the body, leading to complications like:5

  • Heart failure
  • Cardiac arrest
  • Muscle pain
  • Muscle weakness
  • Death

When food is re-introduced, some people in recovery may experience a drop in phosphorous levels. This is because the body needs enough of it to produce ATP, which winds up stealing some from the heart, causing ineffective muscle contractions and may lead to heart failure. It can happen very quickly in people who enter treatment, which is why phosphorous supplements are typically given to patients.

Cardiovascular complications

The heart needs to beat tens of thousands of times a day, and that takes a tremendous amount of energy. The body tends to compensate for lack of energy intake by changing how the cardiovascular system functions.


A regular heartbeat is between 60 and 90 beats per minute, but when a heart is starved due to lack of food consumption, it tends to beat slower to use less energy. As such, many people with eating disorders like anorexia may have a low resting heart rate, below 60 beats per minute.6,7

Of course, not everyone with a low resting heart rate has an unhealthy heart—many athletes have resting heart rates below 60, but that’s because their heart is strong instead of starved. 

Orthostatic hypotension

Orthostatic hypotension refers to a sudden drop in blood pressure or an increase in heart rate when changing positions, such as going from sitting to standing or lying down to sitting up. This commonly occurs in people with eating disorders since the body can’t compensate quickly for a change in posture.6 Some symptoms of orthostatic hypotension include dizziness, blacking out, and fainting.


Acrocyanosis refers to a blueish tint on the extremities due to reduced oxygen reaching those parts. It’s common in eating disorder patients because their circulation is compromised, causing blood to pool in their hands and feet, possibly due to hypothermia.8

Gastrointestinal effects

In a state of malnourishment, the gastrointestinal system slows down and wants to hold onto food as long as possible. Unfortunately, this leads to a host of problems from top to bottom.

Acid reflux

Under typical circumstances, the esophageal sphincter, which separates the stomach and the esophagus, should be very tightly sealed because the stomach produces hydrochloric acid. However, if that seal isn’t extremely tight, it creates a free flow of acid up and down the esophagus. 

This is commonly seen in eating disorder patients, especially those who purge via self-induced vomiting. Vomiting can weaken the esophageal sphincter and loosen that seal between the stomach and esophagus. This can lead to inflammation of the esophagus and ulcers, narrowing of the esophagus from scar tissue buildup, and Barrett’s esophagus, which is a pre-cancerous change, increasing the risk for esophageal cancer.9


Gastroparesis refers to the slowing of the gastrointestinal system. This occurs in eating disorder patients because the body compensates for the lack of food intake by giving it more time to absorb nutrients.6 It can lead to nausea, vomiting, stomach bloating, stomach pain, a feeling of fullness after just a few bites, acid reflux, and changes in blood sugar levels.


Due to gastroparesis, constipation is commonly seen in people with eating disorders. This may happen due to severe food restriction in patients with anorexia or due to laxative abuse, which can damage the colon.6,8

Endocrine system complications

In a state of malnourishment, the endocrine system adapts to allow people to survive; however, these adaptations can ultimately be harmful and affect other areas of the body.

Euthyroid sick syndrome

Euthyroid sick syndrome refers to a condition in which the thyroid appears ill but is not.6 This is because metabolism slows down during states of deprivation, and the thyroid is the driver of metabolism in the body—as such, thyroid hormone levels may be low in order to save energy. This can result in feeling cold, tired, and constipated. But thyroid medication won’t resolve the issue; nourishment will.8

Drop in sex hormone levels

Men with eating disorders may notice decreased testosterone levels, while women will experience reduced levels of estrogen and progesterone. These reduced female sex hormones can result in a shrunken uterus and ovaries, resembling postmenopausal or prepubescent sex organs. This is because the body is in a state of malnourishment, and it recognizes that it doesn’t have the energy required to create a life. Often, menstruating people will experience amenorrhea or a stop in a natural period.8

Bone issues

A serious complication of eating disorders, especially anorexia, is significant bone loss, impaired bone structure, and decreased bone strength. Osteopenia refers to some bone loss, which could be reversible in recovery, and osteoporosis refers to irreversible bone loss. This can occur in all eating disorder patients, even adolescents.6,8

Recovery can help rectify these effects

Although eating disorders have devastating effects on the brain and body, it’s never too late to seek treatment. With professional, integrated, and compassionate care, recovery and restoration are possible, and many of these medical complications can be reversed, fixed, or addressed.


  1. van Hoeken, D., & Hoek, H. W. (2020). Review of the burden of eating disorders: mortality, disability, costs, quality of life, and family burden. Current opinion in psychiatry, 33(6), 521–527. 
  2. Hundemer GL, Clarke A, Akbari A, et al. Analysis of Electrolyte Abnormalities in Adolescents and Adults and Subsequent Diagnosis of an Eating Disorder. JAMA Netw Open, 5(11).
  3. Mehler, P. S., & Brown, C. (2015). Anorexia nervosa - medical complications. Journal of eating disorders, 3, 11. 
  4. Centers for disease control and prevention. (2021). Low blood sugar (hypoglycemia).
  5. Håglin L. (2001). Hypophosphataemia in anorexia nervosa. Postgraduate Medical Journal, 77, 305-311.
  6. Cost, J., Krantz, M.J., and Mehler, P.S. (2020). Medical complications of anorexia nervosa. Cleveland Clinic Journal of Medicine, 87(6), 361-366.
  7. Rome, E.S. and Ammerman, S. (2003). Medical complications of eating disorders: an update. Journal of Adolescent Health 33(6), 418-426.
  8. Mehler, P.S. and Brown, C. (2015). Anorexia nervosa—medical complications. Journal of Eating Disorders, 3, 11. 
  9. Denholm, M., & Jankowski, J. (2011). Gastroesophageal reflux disease and bulimia nervosa—a review of the literature. Diseases of the esophagus: official journal of the International Society for Diseases of the Esophagus, 24(2), 79–85.