The diagnostic concept of binge eating disorder (BED) was introduced in response to the clinical observation of Stunkard (1959) that some people with obesity have recurrent episodes of binge eating. We suggest that the DSM-IV concept of BED has resulted in the recruitment of heterogeneous research samples, amongst which are some people with BED, as described by Stunkard, some with bulimia nervosa, some with other types of eating disorder, and some with no eating disorder. We consider the difficulties distinguishing BED from other forms of overeating, especially in patients with obesity, and from nonpurging bulimia nervosa. We propose revised diagnostic criteria for BED and bulimia nervosa that are designed to minimize these problems. © 2003 by Wiley Periodicals, Inc. Int J Eat Disord 34: S89–S95, 2003.