DSM-IV-TR recognizes three different forms of eating disorder: anorexia nervosa, bulimia nervosa, and eating disorder NOS. A fourth type of eating disorder, binge-eating disorder, is listed in the Appendix and is not yet part of the formal DSM. Both anorexia nervosa and bulimia nervosa are characterized by an intense fear of becoming fat and a drive for thinness. Patients with anorexia nervosa are seriously underweight. This is not true of patients with bulimia nervosa.
Eating disorders are more common in women than they are in men. They can develop at any age, although they typically begin in adolescence. Anorexia nervosa has a lifetime prevalence of around 0.5%. Bulimia nervosa is more common, with a lifetime prevalence of 1–3%. Many more people suffer from less severe forms of disturbed eating patterns.
Genetic factors play a role in eating disorders, although exactly how important genes are in the development of pathological eating patterns is still unclear. The neurotransmitter serotonin has been implicated in eating disorders. This neurotransmitter is also involved in mood disorders, which are highly comorbid with eating disorders. Sociocultural influences are important in the development of eating disorders. Our society places a heavy value on being thin. Western values about thinness may be spreading, helping explain why eating disorders are now found throughout the world. Finally, individual risk factors, such as internalizing the thin ideal, body dissatisfaction, dieting, negative affect, and perfectionism are implicated in the development of eating disorders.
Anorexia nervosa is very difficult to treat. Treatment is long-term and many patients resist getting well. Current treatment approaches include re-feeding, family therapy and CBT. Medications are also used.
The treatment of choice for bulimia nervosa is CBT. CBT is also helpful for binge-eating disorder. Obesity is defined as having a body mass index of thirty or