"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.