10 to 20 pounds over ideal body weight increases diabetes risk substantially, and overeating is thought to be catching up to smoking in causing premature death in this country, to the tune of 400,000/year. A gene in some people may cause increased insulin resistance -
http://www.newscientist.com/article.ns?id=dn7687 - but genetic problems have always been there, yet as a society, we've "ballooned" in the last 30 years. The question is why? Probably the increase in refined foods and sugar is part of it, increased fat consumption (french fries), and less exercise (calories in, calories out).
In one study, rats whose calorie consumption was cut by 30%, added significant longevity and didn't present telltale aging signs, including chronic conditions and an "aged" appearance. Apparently free radicals increase with increased calorie consumption (causing oxidation), and ages you. (That's bad for your dick, by the way.) But imagine cutting out 30% of your daily calorie intake. Not easy.
My brother is a psychologist and has talked from time to time about sublimation. That is, when your sex life goes south, you substitute food. Have you ever noticed when you're "in love" (or "lust"), food is way down on the prioity list. I've always thought one reason couples gain weight over the years is because they're not inspired to have sex.
Regarding fat women, it's a problem to be sure, but not gender-specific. Are there more "in shape" guys than gals? I don't think so. Some guys like "hefty" women, but personally, plump women shut me down, like news of a death in the family. And like fishing for snapper, it gets harder and harder to find plentiful, suitable fish, and that's everywhere, not just the States.