Anorexia nervosa is an eating disorder in which a person refuses to stay at even the minimum body weight considered normal for their age and height. Persons with this disorder may have an intense fear of weight gain and a distorted body image. Inadequate eating or excessive exercising results in severe weight loss.

See also:

• Bulimia
• Intentional weight loss

The exact cause of anorexia nervosa is not known, but social attitudes towards body appearance are believed to play a role.

Causes may include genetic, constitutional, psychological, trauma, family, and society or cultural factors. Any given case is likely due to more than one factor.

Anorexia nervosa usually occurs in adolescence or young adulthood. It is more common in females. The eating disorder is seen mainly in Caucasian women who are high academic achievers and have a goal-oriented family or personality.

Most individuals with anorexia nervosa refuse to recognize (deny) that they have an eating disorder.

Symptoms may include:

• Weight loss of 15% or greater below the expected weight
• Inappropriate use of laxatives, enemas, or diuretics (water pills) in an effort to lose weight
• Self-imposed food intake restrictions, often hidden
• No menstruation
• Skeletal muscle atrophy
• Loss of fatty tissue
• Low blood pressure
• Dental cavities due to self-induced vomiting
• Blotchy or yellow skin
• Depression

A diagnosis of anorexia nervosa is not made until other causes of weight loss are ruled out. The health care provider will determine if endocrine, metabolic, digestive, and central nervous system abnormalities can explain the weight loss. (For example, extreme weight loss could be due to celiac disease, inflammatory bowel disease, Addison's disease, and many other possible conditions.)

Tests will be done to help determine the cause of weight loss or to determine what damage the weight loss has caused cause. They may include:

• CHEM-20
• Urinalysis
• Thyroid function tests
• ECG
• LH response to GnRH

The biggest challenge in treating anorexia nervosa is having the person recognize that their eating behavior is itself a problem, not a solution to other problems. However, most persons with anorexia nervosa deny that they have an eating disorder. Individuals often enter treatment when their condition is fairly advanced.

The goal of treatment is first to restore normal body weight and eating habits, and then attempt to resolve psychological issues. A hospital stay may be needed, especially if the person has lost a lot of weight.

Supportive care by health care providers, structured behavioral therapy, psychotherapy, and anti-depressant drug therapy are some of the methods that are used for treatment. Severe and life-threatening malnutrition may require intravenous feeding.

See: Eating disorders - support group

Anorexia nervosa is a serious and potentially deadly medical condition. By some estimates, it leads to death in 10% of cases. Experienced treatment programs have a good success rate in restoring normal weight, but relapse is common.

Women who develop this eating disorder at an early age have a better chance of complete recovery. However, most people with anorexia will continue to prefer a lower body weight and be preoccupied with food and calories to some extent. Weight management may be difficult, and long-term treatment may be necessary to help maintain a healthy body weight.

Complications can be severe. A hospital stay may be needed.

Complications may include:

• Severe dehydration, possibly leading to shock
• Electrolyte imbalance (such as potassium insufficiency)
• Cardiac arrhythmias
• Severe malnutrition
• Thyroid gland deficiencies which can lead to cold intolerance and constipation
• Appearance of fine baby-like body hair (lanugo)
• Bloating or edema
• Decrease in white blood cells which leads to increased susceptibility to infection
• Osteoporosis
• Tooth erosion and decay
• Seizures related to fluid shifts due to excessive diarrhea or vomiting

If you see that your child is restricting his or her food intake, over-exercising, or is excessively preoccupied with weight, talk to your doctor. Early intervention before abnormal patterns are established can reduce the severity of an eating disorder.

Go to the emergency room, or call the local emergency number (such as 911), if fainting, irregular pulse, seizures, or other severe symptoms develop in a person with anorexia nervosa.

In some cases, prevention may not be possible. Encouraging healthy, realistic attitudes toward weight and diet may be helpful. Sometimes, counseling can help.

American Psychiatric Association. Treatment of patients with eating disorders, third edition. American Psychiatric Association. Am J Psychiatry. 2006 Jul;163(7 Suppl):4-54.

Marcus MD. Eating disorders. In: Goldman L, Ausiello D. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 238.

Morris J, Twaddle S. Anorexia nervosa. BMJ. 2007 Apr 28;334(7599):894-8.