Constipation in anorexia is more than just infrequent bathroom trips. It’s a side effect of how the eating disorder affects gastric function.

Anorexia nervosa, often called “anorexia” for short, is an eating disorder that can cause a severe fear of gaining weight and a distorted body image. People with anorexia may excessively restrict calories, compulsively exercise, and misuse laxatives.

Because anorexia can be associated with a low calorie intake, it’s not often thought of alongside constipation, a bowel condition many people think of as a “buildup” of stool in the body.

Anorexia can cause constipation, but chronic constipation may also contribute to the symptoms of an eating disorder.

Gastrointestinal challenges are common in anorexia and other eating disorders, but the exact prevalence of constipation in anorexia is unknown.

In one 2019 study, researchers analyzed a German registry of people with anorexia nervosa. They found as many as 27.6% of teenage girls living with the condition reported constipation.

In a 2021 review, researchers noted functional constipation, or constipation without a specific systemic cause, is more commonly associated with anorexia than other eating disorders.

Constipation isn’t necessarily a “buildup” of stool. It’s defined as fewer than three bowel movements a week. Bowel movements that do occur are often painful, dry, or hard and feel difficult to pass.

Anorexia can be associated with a too-low intake of solid and liquid nutrients. Digestive system functions can change without important substances like fiber and water.

This too-low intake of nutrients can slow gastric motility, preventing food from passing through the intestinal tract efficiently. This means food waste sits longer in the intestines and colon, with more solid waste building up because gastric emptying is delayed.

In addition to changes in your digestive system, laxative misuse, a common behavior in anorexia, can make constipation worse. Over time, your body becomes used to the laxative, and it takes more of it to generate a bowel movement.

Can constipation cause anorexia?

When you live with anorexia nervosa and then develop constipation, infrequent bowel movements may be a side effect or secondary condition.

Sometimes, however, constipation might come first.

There’s no direct evidence that firmly states living with chronic constipation causes anorexia. However, some research suggests anxiety around gastrointestinal (GI) conditions may contribute to disordered eating habits or may make symptoms of an eating disorder worse.

Constipation is just one way anorexia affects digestive health. Other GI symptoms you may experience when living with anorexia include:

Constipation as a side effect of anorexia can get better when anorexia is treated.

According to a 2019 review, weight rehabilitation may improve the speed of gastric emptying, even before body weight returns to a healthy range.

Weight rehabilitation follows a structured dietary plan that slowly introduces increased caloric intake and nutrient-dense foods. As your balanced eating progresses, your digestive system responds in kind.

A 2022 study found constipation symptoms in anorexia diminish quicker than symptoms of abdominal pain, improving each week during inpatient treatment.

If you’re experiencing constipation with anorexia, talking with a doctor can determine what at-home methods of relief might help.

In general, adding fiber-rich foods to your diet, walking for 10–15 minutes after a meal, and consuming plenty of water can help improve gut motility.

Over-the-counter products, like laxatives or enemas, may not be recommended during eating disorder recovery.

Ways to prevent constipation

Recovery from your eating disorder comes first. As your body and mental health begin to heal, you can focus on relieving constipation and other GI issues by:

  • avoiding regular laxative or enema use
  • going when you have the urge to go — not waiting
  • adding foods good for constipation to your diet, like fruits, vegetables, and whole grains
  • adding gentle movement to your day, like walks or yoga
  • staying hydrated

Psychotherapy, nutritional management, and medications can help treat anorexia. These treatments come together to help restore your physical health at the same time as you address your mental health.

Therapists primarily use family-based therapy (FBT), enhanced cognitive behavioral therapy (CBT-E), and a form of CBT specifically intended for eating disorders (CBT-ED).

You can work with your therapist to learn about the underlying psychological factors behind anorexia, and how to move forward to restructure unhelpful thoughts and instill new, beneficial behaviors regarding body image.

Anorexia can be a potentially life threatening condition. In severe cases, recovery in a supervised care setting can help ensure your vital signs are stable and your immediate physical needs are met.

Constipation in anorexia is a gastrointestinal side effect caused by the slowdown of the intestinal tract.

A lack of nutrients like fiber as well as too little water can make stool hard and dry. It can leave you feeling as though you still need to have a bowel movement even after you’ve gone.

Weight rehabilitation, a part of anorexia treatment, can help improve symptoms of constipation. Your doctor can discuss other relief options that fit your needs.