Why Else Could I Be Fat?

What else can it be other than I just plain eat too much, eat crappy, and am lazy? 

The ONLY explanation there can be in the eyes of society is that too many calories enter my body, period, and this sadly means assumptions are made that I'm holed up in a corner with a bag of chips and a gallon of ice cream, possibly combining the two for an extra-special-super-empty-calorie-packed snack, catching the drips of melted ice cream running down my chin with a spoon and giggling to myself as I ravenously slurp it off the spoon from both sides.

WRONG! But what else can it be you may ask? I'll only discuss how I've come to be Fat.  My reasons are nonmedical and are in fact self-imposed, and yet none of them are excuses. Imagine that.  I have, however, excused things--there is a difference.

Definition of "excuse:"  to offer an apology for; seek to remove the blame of

I don't apologize to anyone for my Fatness other than myself.  I blame nobody but myself.  The deal is the reasons I'm Fat aren't what society believes them to be.  My Fatness has also not changed the person I am.  I am the same person I was when I weighed 129 pounds 19 years ago who today weighs 223 pounds at 5'8" tall, only older. The looks, the assumptions, and the attitudes, however, are much different.

Question Number 1:  Why are Fat people Fat?