Culture. America's culture is telling people being unhealthy (and in effect, fat) is okay. Hell, it's usually taboo to make fun of someone's weight here. So, yes, people are different now than they were several decades back.
There's something not adding up here because of American culture's increasing upward spiral of emphasis on beauty and impossible physical perfection. And it's a tall claim to pin it all on culture. The rise of America's health and obesity problem falls a little too close to the ruination of the American food ecosystem; from the abuse of HFCS, to the increasing amount of shit fake food and additives.
And the thing is, the reason why it's "taboo" to make fun of someone's weight is because that doesn't help. All it does is service one's childish sense of feeling superior to someone else. Note that mocking someone's weight is not the same thing as offering advice; real advice, not just "durr don't eat whopers fattie".
The real problem IMO is that American culture is heavily conflicted. It emphasis the shallowest standards of beauty and perfection, while desiring to profit off selling people bad food, conspiring to insert bad substances into more food, and then profiting further off selling the same people fad diets. So, you know, they can be guilted in to the fad diet because all the magazine covers are plastered with the beautiful people.
Pointing and laughing or even trying to shun people is not, ultimately, the correct tactic. Not on a society wide scale.
It is becoming painfully clear that people are not being taught, from an early age, how to feed themselves and take care of themselves. Pop, commercial culture is being allowed to educate them (and manipulate, and profit, off them). Combine that with a minefield of bad information, bad choices, and boobytrapped food items that surround people, and you get the situation that America is in today.
And to be honest, so did I.
I am now trying to reverse that by eating better and getting active. But to some people it does not matter. Since i look this way now, im a slob who doesn't give a shit. That kind of prejudice bothers me.
And people are saying American culture is telling people it's okay to be fat and unhealthy.
No, American culture is increasingly narcissistic, hypocritical, and cruel. It's all about image, and the beautiful people are more emphasized than ever before. Meanwhile people are kept ignorant and manipulated, not to mention given plenty of reasons to become cynical and uncaring about what to do with their life.