I've just started the Master Cleanse, a fast-cleanse where you drink two liters a day of water mixed with 14 tablespoons of lemon juice, 14 tablespoons of maple syrup, and 1/2 teaspoon of cayenne pepper. Each evening you're supposed to drink 1 liter of saltwater, to really cleanse you. I think I'm going to be skipping that, because I don't want to do that.
So far, so good. I'm not hungry at all, and I think I'm consuming more sugar from the cup of maple syrup than I normally do anyway, so I'm not really feeling any different. I have a small headache and trouble focusing, but I haven't really focused at work in about a week, so I'm hesitant to blame the cleanse. The drink itself is pretty gross because there's way too much sugar in it. I've had about half a liter of my required two liters, and at this point, I'm not really sure how I'm going to manage to drink more than one liter of this stuff. I'm so not hungry that I'm not even wanting to drink this. I'm considering doing it with two or four tablespoons of everything, instead of 14. I think that would taste a lot better, and I'd be more willing to drink it.
I'll keep you posted as things progress, and I would love to hear from anyone else who has done this! If you're interested, there's a good episode of This American Life about a similar (though not the same) cleanse you might like to check out.