go through hell to lose it
It's easy.
Really.
You just don't eat as much.
because they have no self control and eat too much
Well, actually, yes they are.
Sure, there may be some genetic or cultural influence to make them eat too much.
But saying it's okay is like condoning alcoholism.
It doesn't matter WHY the person is an alcoholic/tub of lard. It's still wrong.
(And no, I don't but into the media perception of every women as a size 2 or something. However, fat IS wrong - it's a proven health hazard, inconveniences others, and burdens society as a whole.)
Finally....
the air companies make a bomb in money
mmmm....not so much. You know how much aviation fuel an airliner burns? And what it costs? And that's not counting maintenance costs, pilot pay, foods, entertainment, etc.
If it was such a booming industry, why do you think almost ALL airlines are just barely hanging on, with every other one going out of business on a fairly regular basis?