This differs from the essential features of BN, which include binge eating, and inappropriate methods to prevent weight gain (APA, 1994).
Diagnostic and Statistical Manual of Mental Disorders (fourth edition) criteria for AN include a body weight at a level less than 85% of normal weight for age and height, intense fear of fatness, disturbed experience of body weight or shape, and amenorrhea for at least three consecutive menstrual cycles. AN patients are characterized by a refusal to eat or eat much. Criteria for BN include recurrent episodes of both binge eating and compensatory behaviors such as purging, fasting, or exercising to prevent weight gain; behaviors occur at least twice a week for three months minimum. Self-evaluation is again dependent on body weight and shape. Binging and purging are also characteristic of a type of AN and a subtype of BN includes a non-purging type, complicating the diagnosis of each (APA, 1994; Polivy, 2002).
Incidence of both disorders has increased over the last 50 years, with prevalence rates estimated to range from 3% to 10% of at-risk females between ages 15 and 29 years. BN patients outnumber AN patients by two to one. Reasons for the increase in incidence may be due to the increased awareness and reporting of the disorders. About a third of patients meet diagnostic criteria for a five-year or longer period even after treatment. Mortality rates range from 5% to 8%, however it is also estimated th