I don't support your "challenge" because:
People that can manage without food for a week are either highly trained yogis (you can have prejudices all you want, the fact remains), or people very sick who are on a very harsh regime.
Now, yogis can handle being without food because they know meditation which is mastering over the primal instincts of the body, hence they regulate the emotion of hunger. Plus, meditation is an alternative source of energy, so they get supplies out of somewhere. It's not a starvation as you imagine it is.
People that are very sick, undertake starvation because body has perfect inner mechanism of "eating itself". Meaning, when you are starving it feeds out of itself, first the fat, then less relevant tissues, and the vital organs are last. It's purpose is the body to "eat/destroy" all the bad cells by itself, so when one starts eating, only the healthy cells remain, hence only healthy cells reproduce. But, they do drink a lot of water, and some special prepared fresh juices. MOST IMPORTANTLY, these people are tied to bad. They don't have everyday commitments, this is happening in isolated conditions.
So, if you don't belong in any of the two groups I mentioned above - don't do it. If you are determined to do it, know that drinking ANYTHING other than water is cheating.
You won't make it over day two or three just because of the sugar crises. When your sugar levels will fall, you'll start shaking a lot, and won't be able to function at all. That usually happens around the third day. Good luck, I hope you really REALLY know what you are doing.
