Well, I probably need to check it out in the book again but from what I remember she says that once all the cholesterol stones are out of your liver/gall bladder, your bowel movements will sink.
But, I've also heard that healthy bowel movements float. My parents once went to a seminar where the woman talked about "stinky sinkies" and "light 'n fluffies" and that "light'n fluffies" are the ideal!
My husband says his never float and never have. But then his smell and he has gas so I don't think he's a role model. (I'm putting him on a cleansing diet this summer!).