This is true. There are also, though, other environmental factors that make it harder to maintain healthy weight in postindustrial countries than it was in the past, even if you eat no processed foods, cap your calories and work out regularly. Pharmaceutical and industrial waste in the water supply, Roundup in the grain supply, pesticides, hormones in the meat. Personally I'm swayed by the argument that these are at the root of other issues too, like gluten intolerance.

I'm all for encouraging people to eat healthier but some of this is beyond what an average person can control unless you grow your own food and drink from your own well.