I've done it a few times with great success! It makes the cleanse much more effective without all that food in the way. Actually fasting is a cleanse in its own right, but doing a deliberate Colon Cleanse simultaneously, I think, is fantastic. I felt like a million bucks after a few days (once you get over the hump of the fast, ya know?) I always drink vegetable juices and take minerals and supplements when I fast to make sure I'm getting some nutrition... but I'm sure you already know lots about all that stuff. Good luck to you :)