Congrats Amanda! A few of us have been doing the 3-day diet this week. It's going great here so far!
I would like to add a couple of things though...I don't think it's true that you can't substitute. As long as you do it resonably, it seems to work out fine...I've read people sub yogurt for the cottage cheese and i subed the grapefruit for an orange (because all of the grapefruit looked border-line rotten in the store) and all that meat for vegetarian option like cottage cheese for tuna, gardenburger chik-n-grill for baked chicken, and it seems to be working out really well. Of course you wouldn't have much success if you subed a large pizza for 2 slices of meat

but I think that reasonable substitutions help to make it a palatable diet for those who can't stand some of the items. jmho...
and also, i'm wondering what the "chemical breakdown" explanation is? if you have anymore info, I would be very interested. it seemed just to be a very low fat/cal and balanced carb/protein diet to me?
anyway...congratulations again! it sure is nice to have something that works well enough to keep you motivated, huh?