I think that it really depends on the diet plan that goes with this. My Dr. has a really strict plan that goes with it. I think I will have a good sucesss If I stick with his plan!! He said that 70-90% in one year but, he has a really strict diet plan. If you want me to share it with you I can. Good Luck. You will loose more with by-pass becasue they by-pass a lot of your small intestine so the nutrition can not absorbe. With the band you can still absorb everything you put in you and digest it, that's why the diet is so important with the band. Good Luck | 