If I were in charge of the world, weight gain would no longer be determined by how much you ate. Yes, you read that right. Food - and drink of course - would be for nutrition and enjoyment, but would have absolutely no effect on what you weigh. Now don't get me wrong, copious consumption of alcohol will still have the power to turn you into a legless sot in the evening and a human vomit machine in the morning, so no need to fret about missing out on these necessary rites of passage. And if you want to go the Super Size Me route for the rest of your life, don't forget to leave room for the Krispy Kremes.
But this does not mean the end of obesity. Oh no, no, no. I do, after all, have a depraved and shameless sense of humor. There will be fat people, in fact there will be hordes of corpulent butterballs everywhere you look. But these people will not be overeaters.
They will be assholes.
You see, in my world, being an asshole would make you fat. Weight gain would directly correlate with ignorance, bigotry, homophobia, rudeness, intolerance, racism, vindictiveness, chauvinism, narrow and/or small mindedness - there are a lot more adjectives I could add here, but I think you get the general idea. Even just general boorish behavior will pack on the poundage. Oh, and this will also include hate-mongers disguised as the religious right, liars, and people who talk incessantly on their cell phones when driving. Yes, I'm afraid my plan will not wipe out obesity and the many problems related to it, but it will direct it to the proper recipients.
And this way, you will always be able to see the assholes coming.