Additive effects of mood and eating forbidden foods upon the perceptions of overeating and binging in bulimia nervosa.

We examined the relationship between actual caloric intake and subjective perceptions of amount eaten using self-monitoring data. Forty subjects participated in the study: 20 bulimia nervosa patients and 20 normal controls. All subjects monitored their eating for a 2-week period and rated each eating episode on a Likert-type scale ranging from an undereat to a binge. Estimates of actual caloric intake were compared with these subjective ratings. Bulimics were found to overrate the amount consumed, relative to controls. The effect increased as caloric intake increased. Bulimics' ratings of amount eaten and binging were found to be predicted by the estimate of the actual amount eaten, the type of foods eaten, and the subjects' mood prior to eating, while nonbulimics' ratings were predicted only by the estimated actual amount. Subjective ratings of amount were found to be the best predictor of purgative activity. The results are discussed in terms of a perceptual bias theory, treatment implications, and possible revisions to the current DSM criteria for bulimia nervosa.