I failed. I'll try again, next week!
I do agree that fasting for the long haul isn't a good idea, and everyone (especially those people that are on medication) should first consult with their family doctor - or a few open-minded ones - before making any changes to their diet (especially drastic ones, like in this case here... Though, I haven't consulted with mine!). Now with that said, it's alright to go on a fast (up to 40 days) if you have no health problems (don't take any meds) and if you're in relatively good condition. By the way, this isn't "really" a fast (like a water fast, for example) you do get all the necessary life-sustaining nutrients from the lemons + maple syrup + cayenne pepper, etc. It "really" is OK for the short-term (just make sure you don't go over 40 days, although, many people have... and they're still kicking!).
If you're healthy, then what's a few days of not eating any solid foods going to do - it can't hurt! (the body is like the brain, it's plastic... !)
You wrote something about the metabolism slowing. I've heard of that one and it may very well be true, but it (the body) gets past that hurdle and it becomes a fat-burning - (some muscle, but who gives a damn about 1-2lbs... for every 5-10lbs of fat!) - machine!!!
Anyway, the slowing of the metabolism happens only in the begins (it's the bodies way of preparing), just don't fast for 2-3 days, and THEN, stuff your face (like me)!
Cheerios (just don't eat them while on the fast...)