You incidentally notice a lot of chocolate bar wrappers hidden in the wastebasket in your dorm room. You also notice that your roommate has been spending a lot of time in the bathroom lately. The sound of her vomiting a lot makes you concerned that she might be sick. When you ask the school nurse about your roommate's behavior, the nurse recommends that you ask her to come in and speak with her (the nurse) because she may be suffering from: