I like to fast three to five days on apple juice and lemon water before flushing. The malic acid helps soften stones and the lemon water (or use The Master Cleanse drink) helps clear the digestive tract. Keep the fast short so you won't interfere with bile production, but long enough to clear the bowel. A short juice fast can be especially beneficial for people with a slow transit time through their bowels or those who tend to be constipated. The emptier one is, usually the easier the flush. I would not recommend fasting before flushing to anyone who has never flushed or fasted before, that's asking a lot from your body; but for those who are used to doing some fasting, its a good way to prepare.