1: More people are exercising than they used to. . .
#2: Fewer people are smoking. . . .
#3: Doctors know more than they did. . .
#4: The drugs are better. . .
#1 can’t be it, since most obese people probably don’t jog. I would imagine the second is very powerful–and also somewhat related to quitting smoking, since the average weight gain after quitting is six to eight pounds, and one in ten smokers appears to gain up to thirty pounds. Smoking is much, much worse for your health than being fat. I imagine #3 and #4 contribute as well
The thing is, it could be that the obese are not jogging but that those who are jogging are living longer, thus contributing to an increased average. Moreover, the obese tend not to job because of the stress on their joints, but you can find plenty of obese people at the gym on exercise machines that lessen the impact.
You have to remember that being obese is simply having a BMI over 30. Sometimes we confuse obesity with morbid obesity, but they are not the same. There are plenty of obese people that the average American would describe as chubby. There are gyms full of chubby people.
Indeed, it could be the case that American’s are exercising more and thus living longer because of the obesity epidemic. The public believes that exercise will help them loose weight and thus as we become more obese, more people exercise. As I noted before, I think this is at least in part the intentional result of public health campaigns that “encourage” people to believe exercise is effective at inducing weight loss.