Anorexia nervosa, as characterized by the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), is the refusal by an individual to maintain a minimally normal body weight, is intensely afraid of gaining weight, and exhibits a significant disturbance in the perception of the shape or size of his or her body. Usually weight loss is accomplished primarily through a reduction in total food intake. Additional methods of weight loss include purging (e.g., self-induced vomiting or the misuse of laxatives or diuretics) and increased or excessive exercise. Individuals with anorexia nervosa intensely fear gaining weight or becoming fat. This intense fear of becoming fat is usually not alleviated by the weight loss, in fact, concern about weight gain often increases even as actual weight continues to decrease.
Bulimia nervosa is characterized by binge eating and inappropriate compensatory methods to prevent weight gain. The self-evaluation of individuals with bulimia nervosa is excessively influenced by body shape and weight. Individuals with this disorder are typically ashamed of their eating problems and attempt to conceal their symptoms. Binge eating usually occurs in secrecy, or as inconspicuously as possible. 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. Although the type of food consumed during binges varies, it typically includes sweet and high-caloric foods. Binge eating is characterized more by an abnormality in the amount of food consumed than by a craving for a specific food. Binge eating is typically triggered by negative mood states, interpersonal stressors, or feelings related to body weight, body shape, and food.