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Health A-Z

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Harvard Medical School

What Is It?

Anorexia nervosa is an eating disorder that affects about 1 in 100-200 girls or women in the United States. A person with this disorder limits eating and by definition weighs at least 15% less than his or her ideal weight. At least 90% of cases are in women and the disorder usually begins in adolescence. The weight loss may delay the onset of menstruation or stop it once it has started, Anorexia nervosa rarely occurs before puberty or after age 40. And, although relatively rare, it can occur in men.

A person with this disorder fears being overweight. She may be completely convinced that she weighs too much despite what the scale shows or what other people say. To achieve or maintain leanness, she may exercise obsessively or use laxatives. Because a super-restrictive diet requires exquisite control, she may become extremely careful, inhibited and controlled in other areas of life as well. For example, she may retreat from social contacts or may perform ritual behaviors.

The term "anorexia" literally means having a lack of appetite, but this is misleading because people with the disorder usually have a strong appetite or actively suppress a craving for food. They diet to the point of starvation, and they may even experience pride stemming from the strength implied by such self-denial. The disorder is defined not by whether a person feels hunger but by how much weight he or she has lost.

Although anorexia nervosa appears in many cultures, it is most often diagnosed in industrialized societies, where thinness is often equated with attractiveness.

Many people have anorexia nervosa symptoms without having the full disorder. These symptoms can cause significant distress, particularly in adolescence, where girls and boys may strive for an idealized and unrealistic body image.

The cause of anorexia nervosa is not clear. It is likely a combination of inherited (genetic) vulnerability and environmental factors. Based on decades of research, experts see the disorder as having many elements:

  • Genetic. Anorexia nervosa tends to cluster among biological relatives. Sisters of patients with anorexia nervosa have a 6% risk of having the illness themselves. More distant relations have a risk up to 4%.

  • A variant of depression or anxiety. Anorexia, depression, anxiety and obsessive-compulsive disorder tend to run in families, and many people with anorexia nervosa have symptoms of depression or obsessive-compulsive disorder.

  • Associated with personality traits. People with anorexia nervosa are often given to compulsiveness and perfectionism. The eating may be an extension of, or a strong expression of, those traits.

  • Triggered by fears about becoming an adult. One fear may be related to new sexual feelings and activities that begin in adolescence. Sometimes the illness is triggered by a life event linked to normal development, such as moving away from home.

  • A response to environmental pressures. Cultural influences, including images from television and film and pressure from peers, leave the impression that thin is best. In some professions (for example, ballet dancing or modeling), thinness is highly prized, putting participants at risk. But culture is only part of the story. The illness has been known to have occurred hundreds of years ago, even at times when social pressures and conceptions of ideal body image were quite different.

  • A way to cope with difficult family relationships. Family difficulties can provoke the illness, but their importance may have been overemphasized in the past. Sometimes family problems develop after the disease has started, because a person with anorexia nervosa may test the patience of those she lives with. People with the disorder describe a feeling of power and control over others through their dieting.

In advanced stages of the illness, the restrictive dieting is hard to reverse. At that point, hunger may disappear completely and the pursuit of thinness becomes a way of life. Starvation causes medical complications of its own, such as thyroid problems, anemia and joint pains. Extreme dieting can lead to death in the most severe cases, most commonly because of an irregular heartbeat caused by an imbalance of the salts in the bloodstream.

There are two subtypes of anorexia nervosa, a restricting type and a binging/purging type. A person with the restricting type of anorexia diets, fasts and exercises. People with the binging/purging type eat large quantities of food, then vomit. Many people go back and forth between these two patterns.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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