That's a really good point. I think the fatness does affect the weaker part of the gene pool. In earlier times, when food was less processed and less abundant in general, the thinner people died off due to sickness, starvation, etc. But now, instead of being thin and malnourished, they are fat and malnourished. The abundance, access and availablility of food has changed due to globalization but the key point is, the nutritional value of this food is not better. And this is precisely what is killing people. Instead of no food, you've got people living basically off sugar.  Let's take your point and say the numbers of people with normal BF% truly dwindled. There's the point of the manual labor jobs where it is required you are of a relatively low BF%. These people would become scare, if you can't replace them with robots, they will become more valuable on the job market. Being thinner will become a more noticable asset in the workplace in general. You last longer, you cost less.  This might caused a more forced socialized health care system as the output of a thinner person will be considerably higher than a fat one over time, no matter what the job. The fats will be propped up by the labour of the thin people. At some point, however, this kind of system will collapse, too many diabetic people can cause a health insurance company to collapse without getting backed by some outside funding. The government will have to shift its spending to support such a system, outsource even more labor from the Far East for example.  All the Mexican immigrants and other useless shit they keep pushing into the US is not the answer (even though this is the argument for having open borders and such). When these people realize they get shit handed to them, they will become just like their deluded "open borders" fairy-dust sniffing neo-libs who scream "LET THE CHILDREN STAY"!!! These people don't realize the wetbacks coming in will tear down their little utopian world as soon as they get the chance. Why not support unions and the working class of America? Why not work on getting these people fed properly? What about the military? If you don't have an infantry, you have no military power. Regardless what time period, armies that have had a weak infantry were bound to lose the battle. That's why despite all of America's fancy-schmancy equipment, neither they, nor the Russians could defeat the Afghans, because it's much more difficult to deploy infantry in a place like that. So without fit people, you lose your infantry, and you lose your military might.