Background. There are numerous reports of personality disorder pathology in different eating disorders. However, few studies have directly compared personality pathology in bulimia nervosa, binge eating disorder and obesity. The present study examines group differences in DSM-IV personality pathology, considering the potential utility of understanding personality disorders in terms of diagnosis and dimensional scores.

Method. Eating disorder diagnoses were established using the Eating Disorder Examination interview. Thirty-five bulimia nervosa patients, 15 binge eating disorder patients and 37 obese patients were assessed and compared on the International Personality Disorder Examination using categorical and dimensional personality disorder scores.

Results. For most personality disorders, there was a dichotomy of binge eaters versus non-binge eaters. In contrast, there was a continuum of severity in borderline personality disorder pathology between the groups. The dimensional system of measurement of personality pathology allowed for clearer differentiation between the groups.

Conclusion. The study strongly indicates that personality disorder difficulties are present in patients who binge eat, while obese patients who do not binge eat display significantly less personality disorder pathology. Assessment of bulimia nervosa, binge eating disorder and obesity needs to address personality disorders and pathology. Dimensional markers of personality pathology can be used to supplement categorical diagnoses, providing information about the traits that underlie diagnosis.