When I did my first flush I fasted all day, drinking nothing but water BEFORE the flush, and actually started passing stones about an hour after my 2nd dose of E.S. From what I have read this is rare, but it does tend to disprove what some skeptics claim that the "stones" are actually just the olive oil mixed with bile. I drank a lot of water that day, and I think it was a good thing because of the amount of water you lose during the flush. It has to help with dehydration.