I didn't have one, just liquids the day before to ensure the stomach was empty for the procedure. I was told that in a few years, no one will need the pre op diet; apparently it's to shrink organs like the liver & make the surgery easier. According to my surgeon, as they get more experienced & confident, they won't need people to do this. I take it as a good sign; I've obviously got a great surgeon who didn't need the extra help!
Don't think I could've done longer, one day was hideous...!