"Anorexia nervosa (AN) is a severe, usually relapsing, psychiatric disorder. It has the highest mortality rate of any psychiatric disorder with an estimated adult mortality rate of 5% per decade. It is most predominant among girls and young women with the average age at onset being 15 years. Estimated lifetime prevalence is approximately 2% in females and 0.3% in males although studies have reported rates of up to 4% in females. It is characterized by excessive weight loss due to self-starvation, body image distortion, and immense fear of gaining weight or being fat. There are two subtypes: (1) restricting (AN-R), characterized by restricting food intake with or without compulsive exercise, and (2) binge-eating/purging (AN-BP), characterized by episodes of consuming large portions of food (binging) followed by purging (eg, ipecac- or self-induced vomiting, and/or excessive use of laxatives, enemas, or diuretics). Comorbid psychiatric illnesses (eg, major depression, anxiety disorders, obsessive-compulsive disorder or behaviors) are common among individuals with AN."