The notion that we were built to intermittent fast is based on a couple of faulty logic arguments.
1. Some notion of a predetermined way we "should" be. Some religious people think we were created to be a certain fixed way but that is a faith based idea and not science based. Pretty well no one does anything the way we used to if you go back far enough.
2. But that's the way the cave men were. Well, they may have just been surviving from meal to meal and not as healthy as they could have been. High mortality and low life expectancy seems to back this up. With the evolution of agriculture and predictable regular availability of food, survival and health rates seem to have risen.