A preop diet was recommended but not required by my Doc. I did do it though. I had the shakes twice a day than a small meal for dinner. By the time the two weeks post op liquids were done, I never wanted to see another friggin Protein shake ever again. I was cleared this week for 'regular' food and get my first fill on 8/8.
I think the preop diet helps though. I never needed the bottle of Percocet, just liquid Tylenol for a day and a half and never got any of the gas pains in the shoulders. Was really fortunate.