Hello inyanskan,
I think that fasting would be a very efficient way of removing mercury and other heavy metals from the body, as with any other toxin, but, as a first choice I would use chlorella and Spirulina with which to accomplish the same goals.
After several weeks if not months of using these two superfoods, I would then finish off the cleansing with a series of Water Fasts of 7 to 10 days each with good eating habits in between.
To date, I am not aware of any studies that have confirmed the removal of heavy metals by the body while fasting, but any water fast will enable the body to accomplish its goals of cleansing more quickly and efficiently; something that the body is always attempting to do 24/7.

Regards

chris