Definitions and Epidemiology

Anorexia nervosa (“anorexia”) is a disturbance in body perception that results in fear of gaining weight and refusal to maintain a minimally normal body weight. Bulimia nervosa (“bulimia”) is an obsessive self-evaluation of body shape and weight that leads to a characteristic cycle of binge eating and subsequent actions that prevent weight gain.

Though similar in their relationship with food, these diseases represent two separate psychiatric entities with distinct clinical sequelae. Distinguishing features include the body mass index or height-matched weight and, in women, the presence of regular menstruation. Amenorrhea is a key finding of anorexia in postmenarchal women. Diagnosis requires fulfillment of all criteria listed in the text revision of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (Box 200.1). These diseases do not coexist in the same patient; a patient has either anorexia or bulimia, but never both simultaneously.¹

Box 200.1

DSM-IV-TR Diagnostic Criteria Differentiating Anorexia and Bulimia

Anorexia Nervosa	Bulimia Nervosa
1. Refusal to maintain weight greater than or equal to 85% of expected 2. Fear of gaining weight despite being underweight 3. Disturbance in body perception, excessive influence of body shape or weight on self-evaluation, or denial of seriousness of current weight 4. In women of appropriate age, amenorrhea (defined as at least three consecutive missed menses) while not on hormones Subtype as either restrictive or binge-purge	1. Recurrent episodes of binge eating: a. More food in a discreet period than most people would eat in similar circumstances b. Sense of lack of control over eating episodes 2. Recurrent inappropriate compensatory behavior to prevent weight gain (vomiting, exercise, laxatives, diuretics) 3. Bingeing and compensatory behavior occurring at least twice per week for 3 months 4. Undue influence of body shape or weight on self-evaluation 5. This disturbance does not occur during an episode of anorexia

Anorexia Nervosa

Bulimia Nervosa

1. Refusal to maintain weight greater than or equal to 85% of expected

2. Fear of gaining weight despite being underweight

3. Disturbance in body perception, excessive influence of body shape or weight on self-evaluation, or denial of seriousness of current weight

4. In women of appropriate age, amenorrhea (defined as at least three consecutive missed menses) while not on hormones

Subtype as either restrictive or binge-purge

From American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 4th ed, text rev (DSM-IV-TR). Washington, DC: American Psychiatric Association; 2000.

Anorexia can be divided into the restricting or binge eating–purging subtypes. Restricting patients commonly eat only 300 to 700 calories each day, or they engage in excessive exercise to ward off weight gain. Binge-purging behavior involves intentional vomiting or the inappropriate use of laxatives, enemas, or diuretics in response to even small amounts of consumed food. Bulimia is similarly divided into purging and nonpurging. The subtypes are based on the behavior occurring at the time of diagnosis.²

Anorexia and bulimia are diseases nearly exclusively encountered in North America, western Europe, and Japan. Childhood anxiety disorders may increase the likelihood of these disorders, although no clear cause has been identified for either illness. Women suffer from anorexia and bulimia more frequently than men do. The lifetime prevalence of anorexia varies from 0.3% to 1% for women; men are estimated to have one tenth of that prevalence. Bulimia is more common than anorexia, with a lifetime prevalence of 1% to 3% in women. Similarly, only 10% of bulimic patients are male; these men are more likely to suffer from premorbid obesity. The incidence is further increased in male wrestlers.³