I believe the pre-op diet helps shrink your liver, but also helps prepare you for the post-operative phase. My pre-op diet consisted of a protein shake for breakfast and lunch and then a high protein low carb dinner. The protein shake must be at least 15 grms of protein and less than 10 grms of carbohydrates. Post op diet you are on a clear liquid, full liquid, and a puree phase regular food doesn't start for like 3 months.