Health effects and medical risks of eating disorders

An eating disorder is a mental health condition, but it is also a body condition. Eating too little, binge eating, or trying to get rid of food can strain almost every organ. Some of the harm shows up slowly. Some can be sudden and dangerous.^1,2

This page explains the main ways an eating disorder can affect health, what "refeeding risk" means, and when to get urgent care. It is not meant to scare you. Most of these effects are treatable, and many improve as a person recovers.^1,3 If you want the big picture first, start with the eating disorders overview.

Why do eating disorders affect the whole body?

Your body needs steady fuel, fluid and minerals to run the heart, muscles, brain and gut. When food intake is very low, or when the body keeps losing fluid and minerals, it starts to cut back on non-essential jobs to protect the most important ones. Over time that can slow the heart, thin the bones and shut down some hormones.³

Binge eating brings a different set of strains. And ways of trying to undo eating, such as repeated vomiting or misusing laxatives, can upset the body's fluid and mineral balance fast.^2,4

The risks depend on the type of eating disorder, how long it has lasted, and the person's age and other health problems. Learn more about the types of eating disorders.

A quick map of the main effects

The heart

The heart is a muscle, and it can shrink and weaken when the body is short on fuel. In anorexia nervosa, a slow pulse and low blood pressure are very common. A slow pulse was found in up to 95 out of 100 people in one expert review.³ The same review notes that the heart muscle can get smaller and pump less blood, and that fluid can build up around the heart, often without symptoms. Much of this improves with recovery.³

Some people also have a change on the heart tracing (ECG) called a long QT interval. That means the heart takes longer than usual to reset between beats. It can raise the risk of dangerous rhythms and, in rare cases, sudden death.³

With bulimia nervosa, the main heart risk comes from lost fluid and low potassium. Low potassium can also stretch the QT interval, which can cause palpitations (a pounding or skipping heartbeat), fainting and serious rhythm problems.⁴ Dizziness when you stand up is a common warning sign.⁴

Electrolytes: the body's salts and minerals

Electrolytes are minerals such as potassium, sodium and magnesium. They help nerves, muscles and the heart send signals. Your kidneys and your food keep them in balance.

When the body loses a lot of fluid through vomiting or laxative misuse, potassium and other minerals can drop.⁴ Doctors who treat bulimia say these imbalances are the most common cause of serious illness and death in that disorder.⁵ Very low intake of food and fluid can also upset the balance.⁶

Low potassium may not cause clear symptoms at first. It can bring a fluttering heartbeat, dizziness or fainting.⁴ Treatment is to replace what is low, under a doctor's care, and to stop the cause.⁵

One more point matters here. A normal potassium level does not prove that a person is safe, because people who purge only now and then may still have normal results.⁴

Bones

Bones keep building until about the mid-20s. When an eating disorder starts in the teen years, the body may never reach its full bone strength.³ In one review of anorexia nervosa, about 85 out of 100 women had thin or weak bones (osteopenia or osteoporosis). Men can be affected too.³

Low sex hormones, high stress hormone levels and poor nutrition all play a part.³ The result can be fractures after small falls. A bone density scan (DEXA) is the usual test.³

Bulimia nervosa does not seem to raise the risk of weak bones as much. A person who had anorexia nervosa in the past may still be offered a scan.⁵

The stomach and gut

When the body is under-fed, the stomach may empty slowly. That can cause bloating, feeling full quickly, and belly pain after eating. Constipation is also common.³ These symptoms can make eating feel harder, but they often ease as nutrition improves.³

Some problems are rare but serious. A stomach that stretches too much (acute gastric dilation) can cause severe pain in the upper left belly and needs urgent care.³ The liver can also show stress on blood tests. This is seen in nearly half of people with anorexia nervosa in one review.³

Repeated vomiting can bring acid reflux, a sore throat, hoarseness and trouble swallowing. In rare cases it can injure the food pipe (esophagus).⁴ Long-term laxative misuse can cause ongoing diarrhea, mineral loss and a colon that works poorly. Stopping can cause constipation for a while.⁴

In binge-eating disorder, people may have reflux, bloating and diarrhea.²

Teeth and mouth

Dentists can sometimes spot the signs of repeated vomiting. Stomach acid from repeated vomiting wears away the back of the upper front teeth. Damage can show up in about six months. Cavities, gum disease, sensitive teeth and dry mouth are also common.⁴

Some people have painless swelling of the glands in the cheeks (parotid glands). It can appear a few days after vomiting stops and often fades.⁴ If you have tooth or gum changes, a dentist can help protect your teeth. You do not have to explain everything to get care.

Hormones, periods and fertility

When the body is short on fuel, the brain turns down the signals that control reproductive hormones. In women and girls, periods can stop. Estrogen drops, which also weakens bones.³ In men, testosterone falls.³

Pregnancy can still happen even when periods have stopped or are irregular. An eating disorder during pregnancy can raise the risk of miscarriage and problems for the baby, so tell your doctor.^3,4

Thyroid blood tests may show lower levels. These usually return to normal as nutrition improves.³ In advanced illness, blood sugar can drop very low, which is dangerous.³

NIMH also lists other long-term effects of anorexia nervosa, including anemia (low red blood cells), muscle loss, low blood pressure, harm to the brain and, in teens, delayed puberty.²

Binge-eating disorder and health

Binge-eating disorder can bring type 2 diabetes, heart and blood vessel problems, sleep problems, and gut symptoms like reflux and bloating.² These are medical concerns that deserve care. They are not a reason for shame. Treatment can include medical care along with therapy.² See treatment for eating disorders.

What is refeeding risk?

Recovery means eating regularly again, and that is the goal. But after a long period of eating very little, the body's minerals can be very low. When food returns, the body shifts phosphate, potassium and magnesium into its cells, and blood levels can fall fast.⁶ This is called refeeding syndrome.

It can cause a heart rhythm problem, swelling, weak muscles, trouble breathing, and confusion.⁶ People with eating disorders are one of the groups at higher risk.⁶

Doctors lower the risk with blood tests, slow and planned increases in food, and replacing low minerals and vitamins.⁶ Researchers are still learning the best methods.⁶

What checkups look like

A medical visit for an eating disorder often includes blood pressure and pulse checks, blood tests for minerals, kidneys, liver and blood sugar, and a heart tracing (ECG). A doctor may also order a bone scan.^3,4

Remember that tests can miss problems. A doctor also listens to your symptoms and history.⁴ It helps to bring a list of symptoms, medicines and supplements. You can say, "I am worried about how I am eating," and ask for a check of your heart and blood work.

When to go to the emergency room

Call your doctor soon, within a day or two, for new dizziness, a pounding heartbeat, ongoing weakness, ongoing reflux, tooth damage, or missed periods. You do not need to wait until you feel "sick enough." Early care works best.¹

For signs that are easy to miss, see signs of an eating disorder. To understand why eating disorders start, see causes and risk factors.

Eating disorders in later life

Eating disorders can start or continue after age 50. At that age, these effects can add to other health problems, such as heart disease, thin bones or kidney problems. Read more on eating disorders in midlife and later life.

Getting support

If you are worried about a family member, see helping someone with an eating disorder. Eating disorders often go along with depression and anxiety, and treating them together matters.¹

In the U.S., the National Alliance for Eating Disorders runs a free helpline at 1-866-662-1235, answered by licensed therapists. As of October 2026, its website lists weekday hours, 9 a.m. to 7 p.m. Eastern time.⁷ For a crisis at any hour, call or text 988.

Education only. This page is general information written from the sources listed. It is not medical, legal or financial advice and does not replace a doctor, therapist or lawyer who knows your situation. How we write and check pages.