This review will first describe problems in the definition of the term binge eating, especially in the absence of purging (vomiting, laxative abuse). We highlight current approaches in the classification of obesity, and then provide an overview of the available literature on differences between obese binge eaters and obese non-binge eaters. Many studies indicate that binge eating is common among the female obese, with a frequency ranging from 23 to 46% among those seeking treatment for weight reduction. Despite differences in the definitions of binge eating and variability among the samples investigated, there is strong evidence that binge eaters represent a distinct subgroup among the obese. Binge eating obese exhibit significantly more eating and weight-related pathology, as well as more psychopathology compared to their non-binge eating obese counterparts.