In the current psychiatric nomenclature of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR), the eating disorders consist of two clearly defined syndromes: anorexia nervosa and bulimia nervosa. Many individuals present-ing for treatment of an eating disorder (Figure 58.1) fail to meet formal criteria for either anorexia nervosa or bulimia nervosa, which raises an important theoretical and practical question: What is an eating disorder? Although this topic has received surprisingly little attention, it has been suggested that a working definition of an eating disorder might be “a persistent disturbance of eating be-havior or behavior intended to control weight, which significantly impairs physical health or psychosocial functioning” (Fairburn and Walsh, 2002). This definition clearly encompasses the recog-nized disorders, anorexia nervosa and bulimia nervosa. In addi-tion, it provides a basis for viewing eating disorders as clinically significant problems that do not meet criteria for anorexia nervosa or bulimia nervosa. The term atypical eating disorder is often ap-plied to such problems, even though the number of individuals suf-fering from them may well outnumber those with “typical” eating disorders. One example of an atypical eating disorder is that of women who are overly concerned about their weight, have dieted to a below-normal weight, but have not ceased menstruating and, therefore, do not meet full criteria for anorexia nervosa. Another is that of individuals who binge and vomit regularly, but at less than the twice-a-week frequency required for bulimia nervosa.
An additional example of a clinically important atypical eating disorder is the occurrence of frequent binge-eating that is not followed by the self-induced vomiting or other inappropri-ate attempts to compensate that are characteristic of bulimia ner-vosa. This disturbance, for which the name binge-eating disorder has been proposed (DSM-IV appendix B) is a common behavio-ral pattern among obese individuals who present for treatment at weight loss clinics.
At present, obesity is not considered an eating disorder. Obesity refers to an excess of body fat and is viewed as a general medical, not a psychiatric, condition. At this stage of our knowl-edge, obesity is conceived as an etiologically heterogeneous condi-tion. Obese individuals are at increased risk for a number of serious medical problems and are subject to significant social stigmatiza-tion and its psychological sequelae. However, the widely held as-sumption that obesity is the result of a psychiatric disorder in which eating is used as a coping mechanism for depression or anxiety has not been substantiated by empirical research. Studies of obese and normal-weight subjects from the general (nonpatient) population have found no more psychiatric disturbance in those who are over-weight than in those who are of normal weight.. Therefore, it seems appropriate at present to describe as having an eating disorder onlythose obese individuals who manifest a clear behavioral abnormal-ity that impairs health or psychosocial functioning.