[armchairhacker]

Also even though starvation was much more common back then, people still had access to excess food and didn’t get fat. Some animals will eat until they literally explode. People have a fullness indicator but we ignore it, or it gets shifted towards eating too much.

I’m on the side that we’re overthinking it and a big contributor to obesity is just really bad cultural habits. A lot of people barely exercise at all, even walking, and when they get hungry they grab an unhealthy snack in 5 seconds. Even though are ancestors didn’t understand or care about exercise or getting fat, I doubt they had those habits.

Unfortunately once someone develops those habits, even as a kid, they’re hard to unlearn and they could affect the body’s set point. And they’re so ingrained into our culture that even people who try to be healthy (e.g. by eating a “healthy” fruit bar or exercising 30min on top of their sedentary lifestyle) don’t avoid them.

Now, there are people who got obese even though they exercise and eat whole foods, but I would be surprised if they aren’t a minority.