Since they took control of worrying about how thin we were. Food stamps, government "free" lunches, breakfasts... the feds start fattening us up even while we're unviable tissue masses with programs for the pregnant. Then they run PSAs about all the "hunger" in America. According to the government you suffer from "hunger" if you miss one meal a month. We need to "needs test" the "free" food programs by measuring height and weight of the recipients. Permit real medical loopholes. Let the food police set the standards and the libs run the oversight. Publish their results locally so the libs have incentives to achieve good results . Leave the ability to opt out of the program and associated food police oversight, by just opting not to take the free food - the low liberal diet. You'll probably save enough federal dollars in food give aways to pay for something better for the truly needy weight challenged than a pyramid scheme.
Admittedly this isn't going straight to the libertarian ideal, but it is a step in the right direction and one that is politically possible.
I think people started to bloat once we got away from the idea of four basic food groups -- and once we became so sedentary. Lots of factors in this. I don't think a chart is going to fix it.