Eating disorders are psychological conditions characterized by unhealthy, obsessive, or disordered eating habits. Eating disorders come with both emotional and physical symptoms and include anorexia nervosa (voluntary starvation), bulimia nervosa (binge-eating followed by purging), binge-eating disorder (binge-eating without purging), and other or unspecified eating disorders (disordered eating patterns that do not fit into another category).

Eating disorders occur more frequently in affluent cultures than in non-affluent ones, but they are not exclusive to the well-off. A disproportionate number of those diagnosed are young women in their teens and 20s, but anyone—including young men and older adults of any gender—can develop an eating disorder. Eating disorders often become all-consuming, forcing the afflicted to focus on eating (or not eating) to the exclusion of much else in their life.

Biological factors, social and interpersonal pressures, and family history are some of the factors associated with eating disorders. Culturally mediated body-image concerns and personality traits like perfectionism and obsessiveness also play a large role in the disorders, which are often accompanied by depression or anxiety.

Treatment is rarely simple. Eating disorders may create additional medical problems and can even be acutely life-threatening, requiring hospitalization and forced nourishment. It often takes multidisciplinary teams of health professionals—including psychotherapists, medical doctors, and specialized dietitians or nutritionists—to bring about full recovery.

What Causes Eating Disorders?

There is no single cause of any eating disorder. It's not yet understood why ostensibly voluntary behaviors associated with eating turn into disorders for some people but not for others.

A disturbed relationship with food and a sense of emotional fragility are hallmarks of all eating disorders. Eating disorders typically start out unnoticed––a person eats a little more or a little less food than usual. The urge to eat more or to eat less becomes increasingly compelling until it can become the focus of a person's existence.

Biology also plays a role. Appetite control and the regulation of food intake is highly complex, with many hormones in the brain and the body signaling hunger and satiety. Evidence also suggests that eating disorders have genetic roots.

Culture is thought to also play a significant role, as people—women especially—are pressured to fit an ideal of beauty that is largely defined by weight. Families contribute, too; parents who emphasize looks, encourage dieting, or criticize their children's bodies may be more likely to raise a child with an eating disorder.

Other circumstances factor in, too; the conditions can be triggered by stress, social difficulty, loneliness, depression, trauma, or by dieting itself.

What Is Anorexia?

Anorexia nervosa is an eating disorder marked by an extreme obsession with weight loss or exercise. It is especially prevalent among young to middle-aged women, and increasingly among young men, but it can affect anyone at any age.

Characterized by a distorted sense of body image and extreme voluntary starvation or overexercising—and closely associated with perfectionism and depression—it is the most deadly psychiatric disorder. The most common behavioral signs of anorexia include extreme dieting, obsessive food rituals, and secretive and antisocial behavior.

Anorexia is highly resistant to treatment and is often accompanied by anxiety and depression. Treatment may include cognitive behavioral therapy, medication, nutrition education and management, and family-based therapies, all of which may take place at specialized eating-disorder centers.

If the condition becomes life-threatening, the only recourse may be hospitalization with forced feeding, which may create ethical and legal dilemmas for all caregivers involved.

What Is Bulimia?

Bulimia nervosa is an eating disorder marked by frequent cycles of binge-eating excessive amounts of food, followed by purging. Purging is usually done by self-induced vomiting but may sometimes include the use of laxatives, diuretics, or non-purging compensatory behaviors, such as fasting or overexercising.

The disorder typically begins during adolescence, but it can also develop earlier or later. Regardless of age, it can be difficult to identify because those with bulimia are often secretive about their eating and purging habits. Although many people with bulimia are overweight, they generally have an intense fear of weight gain and often suffer anxiety, depression, and poor self-esteem.

Signs of bulimia include unusual eating behaviors, constant weight fluctuation, frequent use of the bathroom, and avoidance of social events. Treatment usually includes cognitive-behavioral or other forms of psychotherapy, antidepressant medication, and nutrition counseling.

What Is Binge Eating Disorder?

Binge-eating disorder is marked by recurrent episodes of extreme overeating not accompanied by compensatory behavior; as a result, those with the disorder are often overweight or obese.

People with this disorder tend to eat much more rapidly than normal and don't stop until feeling uncomfortably full. They may consume large amounts of food even when they're not hungry. They often eat alone because of shame or embarrassment about their eating behaviors.

Many people experience occasional instances of overeating and may even "binge" from time to time. To be considered a disorder, then, these behaviors must occur at least two days a week for six months or more.

Are There Other Types of Eating Disorders?

Though anorexia, bulimia, and binge-eating disorder are the most well known, eating disorders encompass a number of other conditions, too. These include avoidant/restrictive food intake disorder, rumination disorder, pica, and others.

Avoidant/restrictive food intake disorder is characterized by the avoidance or restriction of food. People with the condition may be uninterested in food—perhaps trying to avoid a negative experience they had in the past, or because they are unsettled by particular sensory characteristics of food, such as its smell or texture.

Rumination disorder is characterized by repeated regurgitation of food after eating, bringing previously swallowed food up into the mouth without displaying nausea, involuntary retching, or disgust. The food is typically then re-chewed and spit out or swallowed again.

Pica is a condition characterized by the eating of one or more nonnutritive, nonfood substances on a regular basis, such as paper, soap, or hair. Those with the disorder typically do not have an aversion to food in general.

Other eating disorders, such as night eating syndrome or atypical anorexia, may be classified under "other specified feeding and eating disorders" in the DSM-5.