Anorexia nervosa, or simply anorexia, is an eating disorder characterized by an extremely low body weight, an irrational fear of gaining weight and severe food restrictions. Symptoms of anorexia may include eating tiny amounts of food or only certain foods, weighing oneself incessantly, excessive exercising, forcing oneself to vomit or using laxatives. Even when anorexia patients are severely underweight, they often see themselves as being too heavy.

Diagnosis of anorexia and severity of the disorder is based on a patient’s body mass index (BMI). Adults with with an extreme case of anorexia tend to have a BMI of less than 15. A BMI of 15-16 would indicate a slightly less lethal but still severe case of anorexia. A BMI of 16-17 would indicate a moderate form of the disorder, and a BMI of 17 or slightly higher would indicate a mild form.

Anorexia is more common among females and is estimated to affect about 0.9% to 4.3% of women in Western countries compared to 0.2% to 0.3% of men. However, men are at greater risk of being under referred, underdiagnosed or misdiagnosed. The disorder typically emerges in the teen years or during young adulthood. Long-term complications of anorexia might include menstruation problems, infertility, anemia, kidney and liver damage, osteoporosis and heart problems.

The disorder appears to stem from a mixture of genetic, cultural and environmental factors. The disorder may be triggered by stressful life events. Higher rates of anorexia are seen among groups that value smaller, fat-free frames such as modeling, dancing and some high-intensity sports. Anorexia was directly related to about 600 deaths worldwide in 2013. It is also indirectly linked to other causes of death, including suicide.

Treatment often involves addressing the underlying psychological issues (such as body dysmorphic disorder) and helping the patient return to a healthy weight. Medications may be used to help with anxiety and depression, which are very common in patients with anorexia. In severe cases, patients may need to check in to a hospital in order to gain weight, overcome malnutrition and receive correct behavioral therapy. When a patient is severely underweight, quick weight gain can be dangerous.

Example: Allison was admitted to the hospital for her long-term anorexia when her BMI eventually dipped below 15.