I have always told people who come to this site to give low carb a good try before resorting to gastric bypass or lap band or Roux-en-Y gastric bypass (RYGB). Why? Because you will be on a low carb high protein diet after you have the surgery. In addition, it seems that you will also be in the hospital a lot more than you would if you didn't have the surgery. So says the latest study out of the Journal of American Medicine: Hospitalization Before and After Gastric Bypass Surgery.
Now, it only covers 1 to 3 years after the surgery, but everyone who is considering the operation should read this article. I also recommend the gastric bypass surgery blog, Living After WLS.