According to this article. It says that if you divide people into four categories-- underweight, normal weight, overweight and obese-- the overweight people have the longest lives. At least, I assume that's what the article means; what it actually says is that overweight people "have a lower death rate." I wouldn't wish to impugn the accuracy of the scientific reporting of the New York Times, but I'm pretty sure the death rate is holding steady at 100% for all groups. :)
But anyway, if overweight people really live longer, we obviously need to redefine the category!