Hi,
I know exactly what your going through. I am on day 13 of my pre-op diet. Quite honestly it gets better. I started of drinking the vanilla flavored Protein shakes from slimfast....horrible...just horrible. I remember people telling me that it takes a couple of days before the shakes start to taste better. That is SOO true. I'm not saying that they will taste delicious after a couple days but there will be a big improvement in taste.
I am currently drinking the Royal chocolate flavored Protein Shakes from Slimfast and I am enjoying them a lot better than the vanilla ones. Sooo....my biggest advice is....be strong for a couple of days...don't give up. It will get better!!