My doctor didn't put me on a pre-op diet either but his reasoning was that I was on the smaller side to have this (bmi of about 38-39) and he didn't feel it was necessary. The nurse at the hospital highly recommended I do liquids the day before to be safe so I would recommend doing that. Her thought was... It can't hurt and we have really good results with that. So I followed her advice.
I was sleeved fri feb 1st so I'm 6 days post-op. I have no regrets but do want to warn that when I woke up in recovery my chest felt like a 500-lb. Man was sitting on it. I hadn't seen anyone else warn about that so in case it happens to you, you're not alone. I do haft say it gradually got way better over the next couple hours but I was in a bit of panic when I woke up in that much pain. I also had a hiatal hernia repaired so I don't know if maybe that had something to do with the pain.
Anyway my doctor told me if I felt hungry and was digesting ok, I could start full liquids before the 2nd week so I had a protien shake last night and all went well. I'm going to try some Greek yogurt later and see how that goes. I have a follow up with my doctor today so well see how that goes.
Good luck and quick recovery to everyone who's going through it!