From that link - this masterpiece from that guy makes it all have about as much credibility as a snake oil salesman:
Another said, "If five days of dry fasting are good, ten days are even better."
So if cutting out a 1/2lb tumor growth from your body is great, maybe 2lb would be awesome.
Yea, the world record for a dry fast is 18 days. The world record for a Water Fast is north of 400 days. So no, you cant double any number that's considered good and say that's better.
Anyway I'd start @ 1 and work on up. Also, I'd lose most of the weight via water so you get the toxins out via water.