Hoodia works great for me. It's getting rarer though so there's lots of stuff out there that's not legit. The stuff I got from Costco works great.
When I used to do my 2 day fasts, I'd use Hoodia and it usually took me to the end of the second day without much hunger. Maybe its cheating somehow, but I don't fast to be miserable with hunger, just to clean out my system.