Hi, My name is Leah and I am having my surgery 3/17 with Dr. Kim, also. I could not tolerate the optifast drinks, so I tried several othe Protein drinks from Whole Foods and they also gave me problems. I talked with Kristen at TLC and she suggested I try the Isopure mix at GNC. I tried the clear bottled drinks and the were fine, except they do not fill you up like the mixes do. I'm going to try the mix tomorrow to see how it does. You might give this a try if the optifast doesn't work.:thumbup: they have buy one, get one half off until the 10th.