I know with the bypass, sleeve or band the protein drinks etc are full of sugar. I had the sleeve done and it has been 8 years. i have had to drink the sugary protein and carb drinks for the first year. after that I was able to eat more at a meal. I can now eat most of what a normal person eats. hence why I have gained weight back. The nuturtionst at the gastic center 8 years ago didnt mention this. but I have found that the bypass etc only last for a specific amount of years. if we dont change the way we eat we go right back to what it was we were eating before thinking the bypass will keep us losing weight or maintain. It does not.