Tieing would cause erosion and would be unsafe. There is the lapband which.is similar to tieing it off. The reason they never undue these surgeries is because they work by restricting your volume of food from several cups down to one.cup or less. If they opened it back up everyone would regain weight as fast as they lost it! It also sections off the part of the stomach that produces ghrelin, the hunger hormone, this helps control hunger in effort to help lose and maintain weightloss.
The procedure doesn't make u anorexic at all, but maybe I misunderstood you, what did u mean by anorexic?