Eating disorders are characterized by the following:
The two main types of eating disorders are anorexia nervosa and bulimia nervosa.
The large majority of eating disorders occur in females and are much more common in industrialized countries where people idealize thinness and have easy access to food. Eating disorders are also much more common in younger women.
The main features of anorexia nervosa are a refusal to maintain a body weight in the normal range, intense fear about gaining weight, and highly distorted body image. In postpubescent women, another symptom of anorexia nervosa is absence of menstrual periods. Anorexia nervosa can result in serious medical problems, including anemia, kidney and cardiovascular malfunctions, dental problems, and osteoporosis.
The main features of bulimia nervosa are habitual binge eating and unhealthy efforts to control body weight, including vomiting, fasting, excessive exercise, or use of laxatives, diuretics, and other medications. People with bulimia nervosa tend to evaluate themselves largely according to their body weight and shape. Unlike people with anorexia nervosa, people with bulimia nervosa typically have body weight in the normal range.
Bulimia nervosa can have serious medical consequences, including fluid and electrolyte imbalances and dental and gastrointestinal problems.
Many different factors influence the development of eating disorders.
Some evidence suggests a genetic vulnerability to eating disorders:
Some researchers have noted that people with eating disorders are more likely to have certain personality traits:
Cultural factors strongly influence the onset of eating disorders. One example is the high value placed on thinness in industrial countries.
Family environment may also influence the onset of eating disorders:
People with eating disorders show distortions of thinking, such as the tendency to think in rigid all-or-none terms. It is unclear whether this type of thinking causes the eating disorders or results from the eating disorders.
The onset of anorexia nervosa is often associated with stressful events such as leaving home for college.