There's a really beautiful double-standard here, though. Why is obesity and related behavior (overeating, choosing unhealthful food, eating more than your metabolism needs/can handle) something which is perfectly normal and out of an individual's hands while nicotine addiction, drug use from mild and largely non-addictive stuff to hard drugs, alcohol consumption, &c. are terrible things that make people evil by association?
Because, y'know, I've got a fucking great metabolism. I can eat whatever I want without gaining an ounce. But I don't, because it's really bad for the body and will still kill you down the line even if there aren't visible signs. If you get fat easily, that's just one more incentive to have some goddamn self control. Society comes down on chronic alcoholics, smoking addicts, drug addicts, &c. for choosing to destroy their bodies, so why not overeating? It's certainly easier or as easy to break free of than any of the others, considering that it's just habitual rather than a chemical addiction.
Or to put it another way, how would you feel if alcoholics started campaigning in the same way, insisting that they aren't hurting themselves and encouraging other people to drink themselves shitfaced as often as possible, to never drink water or milk or juice when booze is available?
All those other things effect people besides the user? Drinking can make you more dangerous to others and smoking causes other people nearby to ingest nicotine whether they want to or not.
If I'm buckled in for an hour-or-more plane flight and I've got some lardass next to me reeking of sweat with their rolls slowly engulfing my arm rest, I'd say I'm pretty goddamn affected, thank you very much.
Not to mention the cases people have already described, with the drain on medical funding and what-not trying to cater to the health problems caused by obesity. Or various indirect affects, like situations where someone's lack of fitness could put others at risk.
Basically, unless you're Jack Black you should try to lose some weight.