On a doco I saw tonight it said he lost 180kg in just under a year, and other stuff i read said it was over a period of 2yrs... which is it? And was the diet changed at all to specifically cater to him? That's nearly 4kg a week isn't it?

I don't know specifically how much he lost byt the end of his first year in the Zone, but there are articles about him on this site that you could easily find with a seaerch. He's made fantastic progress!