I'm on Day 8 of a 10-day MC. I was motivated to cleanse, though I am cautiously optimistic at the weight loss--a collateral benefit. I plan to get right back into WeightWatchers at the end of the fast to keep me on the right track--I already work out several times a week. I don't want to gain back the weight that I lost, and I wouldn't mind dropping a few more lbs so that I can weigh the weight that's noted on my drivers license.
While WeightWatchers isn't for all, it certainly offers a sustainable lifestyle.