> I think a better heuristic, is "Just eat what your great-grandma ate".
Snarky "lead paint?" aside, this only really works if you're also as active as great-grandma was. Chances are she got a lot more exercise than we modern folk do.
"There has been no commensurate decline in physical activity, in either country – in the UK, exercise levels have increased over the last 20 years."
Sure, exercise is important, but a potential lack of it is not the problem. The most significant way you can interact with you body is through the food/drink you put in your mouth.
Food has changed so much over the past few decades that most people no longer eat food but instead consume food like products.
Snarky "lead paint?" aside, this only really works if you're also as active as great-grandma was. Chances are she got a lot more exercise than we modern folk do.