Ms. A was a 16-year-old girl who was hospitalized because of binge eating disorder with a complete loss of control of food intake and a severe major depressive episode including suicidal ideation and self-harming behavior (cutting herself). At hospitalization, her weight was 57.6 kg. Binges occurred at least once a day, and the amount of calories per day was about 5,000. Given the evidence that fluoxetine may be effective in reducing weight, Ms. A was treated with a regimen of fluoxetine, up to 60 mg/day, cognitive behavioral therapy, and dietary management. After several weeks, the depressive symptoms improved, but episodes of bingeing remained unchanged. Thus, we decided to administer, in addition to the described treatment schedule, the opiate antagonist naltrexone, at a daily dose of 100 mg. Within 14 days, we found a robust reduction in binge frequency and the amount of food consumed by Ms. A and weight loss. After discharge, Ms. A was treated with a regimen of fluoxetine (at 60 mg/day), naltrexone (at 100 mg/day), and psychotherapy. Follow-up data after 1 year showed that Ms. A’s weight (49 kg) had remained stable, and she never reported more than 2 binges/month. No side effects were documented. After 1 year, the daily dose of naltrexone was reduced to 50 mg/day, which was followed within 2 weeks by an increase in binge frequency. When we increased the dose of naltrexone to 100 mg/day, the symptoms disappeared again.