Anorexia nervosa is an eating disorder characterized by the refusal to maintain a normal body weight, fears of gaining weight, and an inaccurate perception of the size of shape of one's body. According to the 4th Edition of the Diagnostic and Statistical Manual of Mental Disorders, to be diagnosed with anorexia nervosa, one needs to meet the following criteria:
- Refusal to maintain one's body weight at or above the minimal normal weight for someone of the same age and height.
- Strong fear of gaining weight, even though the person is underweight.
- Inaccurate perception of the body's shape and size, self-image largely dependent on body weight or shape, and/or denial of the seriousness of low body weight.
- Among females, the absence of at least three back-to-back menstrual cycles.
In addition to the above criteria, the DSM-IV identifies two types of anorexia nervosa. The first is called the restricting type. This type is characterized by the absence of binge-eating or purging behavior (for example, self-induced vomiting). The second type is called the binge-eating/purging type. In this type, a person regularly engages in binge-eating or purging behavior.