I know it is the wrong section but, Gastric Byp Surgery is she dying?

What's going on is that an entire section of her GI track was removed. When that happens you're supposed to go on a very strict and special diet. You're not supposed to just continue eating everything you feel like which it sounds like she is doing. It is supposed to make you less hungry so you eat less, but if you fall back into the habit of your old eating patterns you not only have problems gaining all the weight back you also have issues because your GI track is no longer equipped to digest/handle that amount and quantity of food.