For some gastric bypass patients, the surgery emotionally bypasses the real reason they were overweight. If a patient drops a lot of weight without confronting why they were overweight, they risk becoming addicted to something else. Experts call this swap of one compulsive behavior for another "addiction transfer."
Drinking alcohol can be especially dangerous for post-surgery patients because any alcohol consumed bypasses the old stomach and is rapidly absorbed right into the bloodstream, which makes their blood alcohol level spike. Because gastric bypass patients can't eat as much food, there's very little in the stomach to slow the absorption of the alcohol down. Many patients say they start to feel drunk almost instantly.