There are way too many things that changed recently to have conclusions on diets. Environment and chemical residues, sedentary lifestyles, lack of exercise, use

There are way too many things that changed recently to have conclusions on diets. Environment and chemical residues, sedentary lifestyles, lack of exercise, use of drugs (antibiotics and guts flora are now suspected to have interactions) and even more insidious stuff like our social structure changes. And yet many people still manage to live a pretty long and healthy life nowadays with "regular" diets (ie with cereal, yet home prepared and with the right quantity), but not so much while being morbidly obese, drinking water full of lead or smoking... I mean I'm not all against special diets, and to each his own, but this focus on diet as some kind of miracle remedy that let us live better without having to put other efforts into it makes no sense to me.