I don't fast or change my diet at all. The first couple of flushes I tried to follow it by the letter and I always felt horrible. If I eat and drink normally, I don't. I've also did one without the full epsom treatment and I felt it wasn't as good a flush. I think you really need for the stones to move out as quickly as possible so your intestines don't start reabsorbing all the junk. Plus, how can you really see the stones if you aren't kind of cleaned out? I find the epsom goes down best if I chugalug and get it down fast.