Anorexia nervosa is an eating disorder characterized by a relentless pursuit of thinness, a distorted body image, an extreme fear of obesity, and restriction of food consumption, leading to a significantly low body weight.
- Anorexia nervosa usually begins during adolescence and is more common among females.
- People with anorexia nervosa restrict their food intake despite continued weight loss, are preoccupied with thoughts of food, and may deny that they have a problem.
- Severe or rapid weight loss can have life-threatening consequences.
- Doctors base the diagnosis on symptoms and do a physical examination and tests to check for adverse effects of excessive weight loss.
- Treatments that emphasize returning to normal weight and normal eating behaviors (such as individual and family psychologic therapy) can help.
Anorexia nervosa usually begins during adolescence or young adulthood and rarely begins before puberty or after age 40. In a given year, up to 1 in 200 young females have anorexia nervosa. Anorexia nervosa is less common among males. However, mild cases may not be identified.
In areas with a genuine food shortage, anorexia nervosa is rare.
There are two types of anorexia nervosa:
- Restricting type: People limit how much they eat but do not regularly binge eat or purge—for example, by making themselves vomit (called self-induced vomiting) or taking laxatives. Some exercise excessively.
- Binge-eating/purging type: People restrict their food intake but also regularly binge eat and/or purge.
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Causes of Anorexia Nervosa
What causes anorexia nervosa is unknown. Few risk factors for it, other than being female, have been identified.
Genetic and environmental (social) factors play a role in the development of anorexia nervosa. The desire to be thin pervades Western society, and obesity is considered unattractive by many. Even before adolescence, children are aware of these attitudes, and more than half of preadolescent girls diet or take other measures to control their weight. Yet only a small percentage of these girls develop anorexia nervosa.
Other factors, such as psychologic susceptibility, probably predispose certain people to develop anorexia nervosa. Many people who develop the disorder belong to middle or upper socioeconomic classes, are meticulous and compulsive, and have very high standards for achievement and success.
Symptoms of Anorexia Nervosa
Anorexia nervosa may be mild and transient or severe and persistent.
The first indications of the impending disorder may be a subtle increased concern with diet and body weight. Such concerns seem out of place because most people who develop anorexia nervosa are not significantly overweight when the disorder begins. Preoccupation and anxiety about weight intensify as people become thinner. Even when emaciated, people may claim to feel fat, deny that anything is wrong, do not complain about weight loss, and usually resist treatment. They continue to try to lose weight even when friends and family members reassure them that they are thin or warn them that they are getting too thin. People with anorexia nervosa view any weight gain as an unacceptable failure of self-control.
Anorexia literally means lack of appetite, but most people who have anorexia nervosa are actually hungry. Many do not lose their appetite until they are very emaciated.
Also, people with this disorder are preoccupied with food. For example, they may do the following:
- Rather than eat, they study diets and count calories.
- They hoard, conceal, or throw away food.
- They may collect recipes.
- They may prepare elaborate meals for other people.
About 30 to 50% of people who have anorexia nervosa binge and/or purge by vomiting or taking laxatives. The others simply restrict the amount of food they eat. They also frequently lie about how much they have eaten and conceal their vomiting and their peculiar dietary habits. Some people also take diuretics (drugs that cause the kidneys to excrete more water) to reduce perceived bloating and to try to lose weight.
Most women with anorexia nervosa stop having menstrual periods, sometimes before losing much weight. Women and men with anorexia nervosa may lose interest in sex.
Typically, people with anorexia nervosa have a low heart rate, low blood pressure, a low body temperature, and may develop fine soft hair on their body, or excess body and facial hair. Tissues swell because fluid accumulates (called edema). People commonly report bloating, abdominal distress, and constipation.
Self-induced vomiting can erode tooth enamel, enlarge the salivary glands in the cheeks (parotid glands), and cause the esophagus to become inflamed.
Depression is common.
Even when people become very thin, they tend to remain active, often exercising excessively to control their weight. Until they become emaciated, they have few symptoms of nutritional deficiencies.
Hormonal changes resulting from anorexia nervosa include markedly reduced levels of estrogen (in women), testosterone (in men), and thyroid hormone and increased levels of cortisol.
If people become severely malnourished, every major organ system in the body is likely to be affected. Bone density may decrease, increasing the risk of osteoporosis.
Rapid or severe weight loss can cause life-threatening problems. Problems with the heart and with fluids and electrolytes (such as sodium, potassium, and chloride) are the most dangerous:
- The heart gets weaker and pumps less blood through the body:
- Heart rhythm may become abnormal.
- People may become dehydrated and prone to fainting.
- Potassium and sodium levels in the blood may decrease.
Vomiting and taking laxatives and diuretics can worsen the situation. Sudden death, probably due to abnormal heart rhythms, may occur.
Diagnosis of Anorexia Nervosa
- A doctor's evaluation
- Tests to check for problems due to anorexia nervosa
Because people do not think they have a problem, they resist evaluation and treatment. Usually, they are brought to the doctor’s office by family members, or they come because of another disorder.
Doctors measure height and weight and use the results to calculate the body mass index. Doctors also ask people how they feel about their body and weight and whether they have other symptoms. Doctors may use questionnaires developed to detect eating disorders.
Doctors also check for other disorders that can cause weight loss or a reluctance to eat, such as schizophrenia, depression, disorders that interfere with the absorption of food (malabsorption), amphetamine abuse, and cancer.
If people have the following, anorexia nervosa is more likely:
- Restriction of eating that results in a low body weight, usually with a BMI of less than 17 (or for children, a BMI less than the 5th percentile for their age or less than what is expected based on prior growth—see CDC Growth Charts)
- Fear of obesity
- A distorted body image and/or denial that they have a serious disorder
Anorexia nervosa may be diagnosed in children and adolescents who have not lost weight but have not grown as expected because they restrict their food intake.
Doctors also do a physical examination and blood and urine tests to check for effects of weight loss and undernutrition. A bone density test may be done to check for loss of bone density. Electrocardiography (ECG) may be done to check for abnormal heart rhythms.
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Prognosis of Anorexia Nervosa
Without treatment, nearly 10% of people with severe anorexia die. When symptoms are mild and unrecognized, people rarely die.
With treatment, people with anorexia nervosa may have the following outcomes:
- About one half of people regain most or all of the weight they lost, and hormonal and other physical problems due to the disorder resolve.
- About one fourth improve some, gaining some weight back, but they may periodically return to their former eating habits (relapse).
- The remaining one fourth have frequent relapses and continue to have physical and mental problems due to the disorder.
Children and adolescents treated for anorexia nervosa have better outcomes than adults.
Treatment of Anorexia Nervosa
- Measures to ensure that people consume enough calories and nutrients
- Psychologic therapy
- For adolescents, family therapy
- Regular check-ups
Restoring body weight quickly is crucial when the following has happened:
- Weight loss has been rapid or severe.
- Weight has fallen below about 75% of the recommended body weight.
People with anorexia nervosa may need to be hospitalized to ensure that they consume enough calories and nutrients. Eating solid food is the best treatment, but sometimes liquid supplements are also given. Rarely, people who are severely undernourished or who resist eating food need to be fed through a tube inserted through their nose and down their throat into their stomach (nasogastric tube).
Doctors also treat any problems due to anorexia nervosa. For example, if bone density has been lost, people are given calcium and vitamin D supplements.
During hospitalization, psychiatric and nutritional counseling are provided. Hospitalization also helps by taking people out of their normal circumstances and disrupting their dysfunctional eating habits and behaviors. Thus, it may reverse a downhill course. However, most people are treated as outpatients.
Psychologic therapy that emphasizes establishing normal eating habits and attaining a normal weight is often used. Such therapy includes individual and family psychologic therapy, such as cognitive-behavioral therapy. Typically, therapy is continued for 1 full year after people have regained the lost weight. It may take up to 2 years.
Family therapy is useful for adolescents. It can improve interactions among family members and teach parents to help the affected adolescent regain the lost weight.
Psychotherapy is more effective for adolescents who have had the disorder for less than 6 months.
Psychotherapy is particularly important because many people with anorexia nervosa are somewhat reluctant to be treated or to regain weight.
Treatment also involves seeing a doctor regularly for check-ups. Treatment often involves a team of health care practitioners, including a nutritionist, who may provide specific meal plans or information about the calories needed to restore weight to a normal level.
There are no specific drugs to treat anorexia nervosa. However, newer antipsychotic drugs, such as olanzapine, may help people gain weight.
More Information about Anorexia Nervosa
The following are some English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
- National Eating Disorders Association (NEDA): Large nonprofit organization that provides access to online screening tools, a helpline, forums, and a variety of support groups (some virtual)
- National Association of Anorexia Nervosa and Associated Disorders (ANAD): Provides access to curricula and training for medical and health care professionals, as well as peer-to-peer support groups, self-help, and other services
- National Institutes of Mental Health (NIMH), Eating Disorders: A clearinghouse for information on eating disorders, including statistics on prevalence, brochures and fact sheets (also available in Spanish), education and awareness campaigns, and information on relevant clinical trials
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