The elephant in the room is a combination of bullshit from governmental agencies (the lie of the food pyramid anyone?), nonsense from the medical community (fat in our diet isn’t the driver of cardiovascular disease or obesity, it’s unstable glucose, something that’s been well known since the early 90’s), pushing a high-carb diet in the 80’s, which was a lie that ran counter to what doctors advised for diabetetics since the 1930’s!

100% correct, but this also speaks to factors other then just behavioral.

Surely you could say eating carbs, avoiding fat is a behavioral choice - but really people are given so much advice even from their primary care giver, that they follow advice that puts them into a super difficult position to recover from. Even if someone follows the advice perfectly, low fat, high carb whole food diet, they could still have metabolic syndrome (which is more then just visible fat), due to the bad advice they are given.