I just thought I'd jump in here and tell you my experience...I did an 8 day MC, then on the day of my Liver Flush I had some juice (my favourite: carrot apple beet ginger mmm mmmm!), just to get my stomach ready for later. Then I had some more lemonade and some more right up until 2 hours before the first Epsom Salt drink. Then the next day I had some juice after my last epsom drink and made my vegetable soup, drank the broth first etc.
This was my first Master-Cleanse and my first liver flush. I hadn't done the parasite cleanse yet and all went just fine. So far I have found that when I fast before a Liver Flush I feel excellent for the flush (no nausea at all).