I was doing a bit more research and have come to understand that after X amount of time water fasting, your digestive system will kind of shut down and your metabolism will slow donw. That's why you re-introduce food very gradually into your system one week at a time. And the first thing you should take in is natural fruit juice, then fruit pulp and work your way up to raw foods.
So while I was mapping out my fasting plans (which start tomorrow, BTW) I was thinking about ways to keep my metabolism up while fasting. And while I was half-napping, an idea came to me about it: rotating.
I think I'd need a little more research, but I think it may work very well if you're like me and have a LOT of weight to lose and detoxifying to do. Do one solid seven days of eating raw, juicy fruits and fresh fruit pulp, some easy to digest veggies and lots of water. One week of juice fasting, followed by one week of strictly water fasting, and then another of juice, leading into another week of raw fruits like in the first week.
By having one week of eating raw, healthy fruits your digestive system wouldn't shut down and really forget how to digest it; by alternating weeks of juice fasting you would still be putting nutrients into your body and because juice is a foodstuff, your metabolism shouldn't slow down as much and still allow you to lose; and by having a solid week of strictly water you would be able to detox your body.
I'm not solid on it and still need more research, but I really think that this might be a good way to go about fasting for some people. I'd love some feedback and critiques from anyone who's well-versed in fasting or has some medical background to confirm or deny my theories (but I'd love feedback from everyone, so please tell me what you think!)