Honestly the behavioral lifestyle of modern humans is so far off from what we developed that diet is probably a drop in the bucket relative to many other factors. Consider how much movement a persistent hunter in a tribe still engaging in these practices does compared to the modern human, who sits for 95% of the day. The elders in these tribes look lean and still might engage in hunts. The elders in our tribes frequently can hardly walk or access the second floor of their house without difficulty. We went from a species that has to go out and forage or hunt for resources, into one that basically sits in a cave all day and poof there is a couple thousand calories in front of them that they didn’t have to get; no species operates like this. The things that made us humans and improved our fitness to allow us to survive and colonize the globe, our intelligence and endurance or strength, are no longer being selected for in modern life.

Then consider the arbitrary stress that society puts on us. How you dress should not matter, what you love, how you work, where you work, what you do for fun, etc, but we make people hand wring about it all. We have a cruel society in many ways that stifles unorthodox thought and behavior that doesn't ultimately further someone else's dollar. The daily stress of sitting in traffic or waiting for the bus to finally show up on a hot day definitely triggers stress responses. How about the fact that social media has sapped many peoples attention span? The mind is no longer allowed to be bored or to rest or dwell inwardly if you are constantly using every available second to check a website on your cellphone. You see it in kids an adults everywhere: elevator door shuts and out go the phones along with any chance of serendipitous organic thought that doesn't come from an advertising network.

Experiment with your diet, sure, but don’t neglect the other ills of modern life if you want to be truly heathy in body and mind.