The aim of the present study was to investigate the predictive factors for the development of binge eating in restricting anorexia nervosa patients who underwent an outpatient treatment. The sample was a group of 168 patients with restricting anorexia nervosa, consecutively admitted to an outpatient unit. All the patients underwent a routine baseline assessment. Information regarding binge eating onset and duration of treatment was prospectively recorded in clinical records. Twenty-three patients developed binge episodes during outpatient treatment. High scores on the Eating Disorders Inventory body dissatisfaction subscale and early age at menarche significantly predict the risk of developing binge eating. High levels of ineffectiveness, as measured by the Eating Disorders Inventory, and early age at menarche are significant predictors of a shortened time to develop binge eating. The identification of subjects at risk for developing binge eating should be considered an important step for a successful treatment of restricting anorexic patients.