What is the pre op surgery diet. I've seen a few different ones

They really vary, there is no standard one. Different surgeons, different pre-ops. Many times the BMI factors in to what kind or how long a pre-op diet lasts.

Every surgeon has a different diet. The point is to shrink the liver. In order for the liver to shrink you need to have very little sugar and fat. My surgeon required a 12 day liquid diet. I had 4 Protein shakes per day and was allowed broth and sugar-free Jello. The first 3 days were the hardest and then my body adjusted. I advise cutting out sugar as much as possible now. Ween yourself down and that will make it easier.