DEFINITIONS AND EPIDEMIOLOGY
Anorexia nervosa is characterized by refusal to maintain normal body weight, resulting in a body weight <85% of the expected weight for age and height. Bulimia nervosa is characterized by recurrent episodes of binge eating followed by abnormal compensatory behaviors, such as self-induced vomiting, laxative abuse, or excessive exercise. Weight is in the normal range or above. Binge eating disorder is similar to bulimia nervosa but lacks the compensatory behavior element. As a result, binge eating disorder is typically associated with obesity.
Both anorexia nervosa and bulimia nervosa occur primarily among previously healthy young women who become overly concerned with body shape and weight. Binge eating and purging behavior may be present in both conditions, with the critical distinction between the two resting on the weight of the individual. The lifetime prevalence of anorexia nervosa is 1%, that of bulimia nervosa 1–3%, but mild forms of occasional bulimia may occur in up to 5–10% of women. Binge eating disorder has a 4% prevalence. There is a 10:1 female to male ratio for both conditions; binge eating disorder is more evenly divided between women and men (2:1). The typical time of onset of anorexia is mid-adolescence, that of bulimia in early adulthood. Both can occur later, but onset is uncommon after age 40.
Anorexia and bulimia nervosa are disorders of the affluent, well-educated societies in Western cultures. Affected pts frequently exhibit perfectionist and obsessional tendencies. Pursuit of activities that emphasize thinness (ballet, modeling, distance running) are prevalent, as is a drive for high scholastic achievement. Risk factors are a family history of mood disturbance, childhood obesity, and psychological or physical abuse during childhood.
The diagnostic features of anorexia and bulimia nervosa are shown in Tables 210-1 and 210-2.
TABLE 210-1DIAGNOSTIC FEATURES OF ANOREXIA NERVOSA |Favorite Table|Download (.pdf) TABLE 210-1DIAGNOSTIC FEATURES OF ANOREXIA NERVOSA
|Refusal to maintain body weight at or above a minimally normal weight for age and height. (This includes a failure to achieve weight gain expected during a period of growth leading to an abnormally low body weight.) |
|Intense fear of weight gain or becoming fat. |
|Distortion of body image (e.g., feeling fat despite an objectively low weight or minimizing the seriousness of low weight). |
|Amenorrhea. (This criterion is met if menstrual periods occur only following hormone—e.g., estrogen—administration.) |
TABLE 210-2DIAGNOSTIC FEATURES OF BULIMIA NERVOSA |Favorite Table|Download (.pdf) TABLE 210-2DIAGNOSTIC FEATURES OF BULIMIA NERVOSA
|Recurrent episodes of binge eating, which is characterized by the consumption of a large amount of food in a short period of time and a feeling that the eating is out of control. |
|Recurrent inappropriate behavior to compensate for the binge eating, such as self-induced vomiting. |
|The occurrence of both the binge eating and the inappropriate compensatory behavior at least twice weekly, on average, ...|