Speaking as one who is not only fat, but morbidly obese, i can tell you why i think he jokes about his weight: it's less hurtful when you hear the words coming out of your own mouth than out of others'. You try to beat the other to the punch line (as well as the punch bowl, ba da BING!).
See how easy it is?
it becomes a part of who you are, it's like your next breath. i honestly believe some people really don't realize they do it. others, like myself, do it because for whatever reason, it seems to make those we're talking to more comfortable, and maybe even fools them into thinking that we're really ok with how we are.
I hope Tony is really, truly comfortable with how he is (and in my opinion, he should be, except i'd LOVE to have him grow his hair long again, sorry Lizard, haha!)
that, friends, is my 2 cents....
"Faith is believing in things when common sense tells you not to"