EDIT: And I'm way underweight. Why do so few people heckle me when it could easily stunt my growth (didn't, in my case, lol) whereas being overweight can...what? Shorten your life a few uncomfortable years?
Because chances you're someplace where you wouldn't be bothered about being overweight either.
Not to mention being underweight is generally percived as being much easier to fix, weather or not it actually is.
Okay, let's step back into reality.
This would never happen. Ever.
It's not like they'll look up to one fat person for being fat.
But in general socicity seems not only to have stopped caring, but to go out of it's way to make unhealthy people not see the need for a lifestyle change.