How could anyone eat that much? Even when I was at my heaviest I wasn't consuming more than 2,700, if that.
I don't really think his diet tips are going be anymore useful than any other diet book out there (eat less, move more.) I suppose the only aspect he could help dieters with is the emotional side of being extremely obese and the consequences that can have on someone's state of mind.
Good for him losing the weight though.