Diagnostic Features

The essential features of Bulimia Nervosa are binge eating and inappropriate compensatory methods to prevent weight gain. In addition, the self-evaluation of individuals with Bulimia Nervosa is excessively influenced by body shape and weight. To qualify for the diagnosis, the binge eating and the inappropriate compensatory behaviors must occur, on average, at least twice a week for 3 months (Criterion C).

A binge is defined as eating in a discrete period of time an amount of food that is definitely larger than most individuals would eat under similar circumstances (Criterion A1). The clinician should consider the context in which the eating occurred--what would be regarded as excessive consumption at a typical meal might be considered normal during a celebration or holiday meal. A "discrete period of time" refers to a limited period, usually less than 2 hours. A single episode of binge eating need not be restricted to one setting. For example, an individual may begin a binge in a restaurant and then continue it on returning home. Continual snacking on small amounts of food throughout the day would not be considered a binge.

Although the type of food consumed during binges varies, it typically includes sweet, high-calorie foods such as ice cream or cake. However, binge eating appears to be characterized more by an abnormality in the amount of food consumed than by a craving for a specific nutrient, such as carbohydrate. Although individuals with Bulimia Nervosa consume more calories during an episode of binge eating than persons without Bulimia Nervosa consume during a meal, the fractions of calories derived from protein, fat, and carbohydrate are similar.

Individuals with Bulimia Nervosa are typically ashamed of their eating problems and attempt to conceal their symptoms. Binge eating usually occurs in secrecy, or as inconspicuously as possible. An episode may or may not be planned in advance and is usually (but not always) characterized by rapid consumption. The binge eating often continues until the individual is uncomfortably, or even painfully, full. Binge eating is typically triggered by dysphoric mood states, interpersonal stressors, intense hunger following dietary restraint, or feelings related to body weight, body shape, and food. Binge eating may transiently reduce dysphoria, but disparaging self-criticism and depressed mood often follow.

An episode of binge eating is also accompanied by a sense of lack of control (Criterion A2). An individual may be in a frenzied state while binge eating, especially early in the course of the disorder. Some individuals describe a dissociative quality during, or following, the binge episodes. After Bulimia Nervosa has persisted for some time, individuals may report that their binge-eating episodes are no longer characterized by an acute feeling of loss of control, but rather by behavioral indicators of impaired control, such as difficulty resisting binge eating or difficulty stopping a binge once it has begun. The impairment in control associated with binge eating in Bulimia Nervosa is not absolute; for example, an individual may continue binge eating while the telephone is ringing, but will cease if a roommate or spouse unexpectedly enters the room.

Another essential feature of Bulimia Nervosa is the recurrent use of inappropriate compensatory behaviors to prevent weight gain (Criterion B). Many individuals with Bulimia Nervosa employ several methods in their attempt to compensate for binge eating. The most common compensatory technique is the induction of vomiting after an episode of binge eating. This method of purging is employed by 80%-90% of individuals with Bulimia Nervosa who present for treatment at eating disorders clinics. The immediate effects of vomiting include relief from physical discomfort and reduction of fear of gaining weight. In some cases, vomiting becomes a goal in itself, and the person will binge in order to vomit or will vomit after eating a small amount of food. Individuals with Bulimia Nervosa may use a variety of methods to induce vomiting, including the use of fingers or instruments to stimulate the gag reflex. Individuals generally become adept at inducing vomiting and are eventually able to vomit at will. Rarely, individuals consume syrup of ipecac to induce vomiting. Other purging behaviors include the misuse of laxatives and diuretics. Approximately one-third of those with Bulimia Nervosa misuse laxatives after binge eating. Rarely, individuals with the disorder will misuse enemas following episodes of binge eating, but this is seldom the sole compensatory method employed.

Individuals with Bulimia Nervosa may fast for a day or more or exercise excessively in an attempt to compensate for binge eating. Exercise may be considered to be excessive when it significantly interferes with important activities, when it occurs at inappropriate times or in inappropriate settings, or when the individual continues to exercise despite injury or other medical complications. Rarely, individuals with this disorder may take thyroid hormone in an attempt to avoid weight gain. Individuals with diabetes mellitus and Bulimia Nervosa may omit or reduce insulin doses in order to reduce the metabolism of food consumed during eating binges.

Individuals with Bulimia Nervosa place an excessive emphasis on body shape and weight in their self-evaluation, and these factors are typically the most important ones in determining self-esteem (Criterion D). Individuals with this disorder may closely resemble those with Anorexia Nervosa in their fear of gaining weight, in their desire to lose weight, and in the level of dissatisfaction with their bodies. However, a diagnosis of Bulimia Nervosa should not be given when the disturbance occurs only during episodes of Anorexia Nervosa (Criterion E).