There are many who believe that 'fasting' is a great way to detoxify oneself. There are those who think fasting is a great way to kill yourself.
Although I've tried a couple of times to fast on water alone, I've lacked the willpower to go more than 3 days without food.
The basic idea/theory/mumbo-jumbo is this: (I'm not an expert on this, okay? You need to ask this of professionals - on both sides of the arguement, not arfcom wannabe know-it-alls.)
First you burn off all the carbs stored in your body (liver, bloodstream etc). Then you burn protein and fat through ketosis. The protein you burn (this is where it gets into the non-proven or wishful thinking) are the old, infirm, dieing and basically crappy cells. All the sites on fasting I've hit have stated (as fact more than belief, but belief it is), that the body searches out old dieing cells first, along with all the crap stored in the cells. I've seen no scientific backing of this.
It's something that has intrigued me. I'd still like to try it for 10 days just to see for myself. The fasting types believe that somewhere after 11 to 15 days the body resorts to burning "useful" and "healthy" proteins/cells, which by definition is starving. Prior to that, it burns and uses the waste.
As I've said before, this place is filled with people of strong opinion, but rarely of real professional background. Go to both sides of the argument and check it out. I'm not sure of the answer myself. I will not pretend to know the answers. I only know some of the thoughts behind the basic theories.
We are not the medical community. Go to a forum of doctors or biology experts, and ask them. We are gun owners and are therefore NOT qualified to answer your questions in this.