Diagnosis and Differential Diagnosis
Bulimia nervosa typically begins after a young woman who sees herself as somewhat overweight starts a diet and, after some ini-tial success, begins to overeat. Distressed by her lack of control and by her fear of gaining weight, she decides to compensate for the overeating by inducing vomiting or taking laxatives, methods she has heard about from friends or seen in media reports about eating disorders. After discovering that she can successfully purge, the individual may, for a time, feel pleased in that she can eat large amounts of food and not gain weight. However, the epi-sodes of binge-eating usually increase in size and in frequency and occur after a variety of stimuli, such as transient depression or anxiety or a sense that she has begun to overeat. Patients of-ten describe themselves as “numb” while they are binge-eating, suggesting that the eating may serve to avoid uncomfortable emotional states. Patients usually feel intensely ashamed of their “disgusting” habit and may become depressed by their lack of control over their eating.
The binge-eating tends to occur in the late afternoon or evening and almost always while the patient is alone. The typi-cal patient presenting to eating disorders clinics has been binge-eating and inducing vomiting five to 10 times weekly for 3 to 10 years. Although there is substantial variation, binges tend to contain 1000 or more calories and to consist of sweet, high-fat foods that are normally consumed as dessert, such as ice cream, cookies and cake. Although patients complain of “carbohydrate craving”, they only rarely binge-eat foods that are pure carbo-hydrates, such as fruits. Patients usually induce vomiting or use their characteristic compensatory behavior immediately after the binge and feel substantial relief that the calories are “gone”. In reality, it appears that vomiting is the only purging method capa-ble of disposing of a significant number of ingested calories. The weight loss associated with the misuse of laxatives and diuretics is primarily due to the loss of fluid and electrolytes, not calories.
When not binge-eating, patients with bulimia nervosa tend to restrict their calorie intake and to avoid the foods usually con-sumed during episodes of binge-eating. Although there is some phenomenological resemblance between binge-eating and sub-stance abuse, there is no evidence that physiological addiction plays any role in bulimia nervosa.