Among women, the lifetime prevalence of anorexia nervosa is 0.5 to 1% and of bulimia nervosa about 4%. Most commonly, the disorder starts in adolescence, often precipitated by a stressful life event. When anorexia nervosa occurs in prepubertal children, it tends to be part of more severe psychopathology, but it is also more likely to resolve. Females are affected 10 times more often than males. The eating disorders tend to be diseases of Westernized countries. In the United States, Whites are more often affected than African Americans or Hispanic Americans.

A combination of biologic, psychological, environmental, and social factors has been implicated in the pathogenesis of eating disorders. Both anorexia and bulimia nervosa are more
common in high-risk groups that require highly focused attention on weight and appearance, such as ballet, ice-skating, and other sports. High achieving, perfectionistic, competitive individuals with underlying low self-esteem tend to be more commonly affected. Mood disorders, anxiety disorders, substance use, and personality disorders tend to be common comorbidities. Individuals with anorexia nervosa tend to be exquisitely sensitive to perceived rejection, hostility, and conflict. From a family theory perspective, anorexic families often present a conflict-free exterior. This façade is thought to mask a lack of intimacy, enmeshment, rigidity, and conflict. The symptoms of anorexia are thought to focus the family away from the conflict and thus maintain family “homeostasis.” In fact, once a pattern of disordered eating begins, multidetermined factors maintain and promote the dysregulated eating patterns. These may include stabilization of the family, binding of anxiety and dsysphoria, and positive reinforcement emanating from compliments about weight loss that may be received from coaches or friends.