I was given pre-op calorie drinks the night before and the morning of the operation, they say keeping hydrated and having a good calorie intake helps your body recover and reduces the chance of insulin resistance.
I had a low residue diet to follow for 5 days before and was allowed to eat this until midnight the night before. I did have bowel prep though.
I dont know if it makes a difference as i dont have anything to compare it to but I was out of hospital 4 days after the operation.