OBJECTIVE: Stress plays a role in the pathology of bulimia nervosa and binge eating disorders, but it is unclear whether they involve similar disturbances of biological stress responses. PATIENTS AND METHODS: We recruited 25 patients with binge eating behavior, 12 with bulimia nervosa (BN) and 13 with binge eating disorder (BED), and compared them with 13 obese non-binge eaters (NBED). We measured heart rate variability in response to mental stress tasks, and concentrations of leptin, glucose and insulin in the blood. RESULTS: Heart rate stress reactivity was highest in BN patients. Heart rate variability did not change during mental stress in BN and BED patients, but reduced as expected in the NBED group. During post-stress recovery, heart rate variability decreased in BN, was maintained in BED and increased as expected only in the NBED group. CONCLUSIONS: BN and BED patients exhibit limitations in autonomic stress reactivity and recovery capacity.