Our ancestor regularly consumed vegetables, especially cruciferous vegetables. Nuts were a great source of energy and could be kept stored. Meat was intermittent and hunting takes high energy. It’s hard to imagine maintaining the average American diet a thousand years ago.
Try for a moment to envision an average person a millennia ago. As she rises every day, does she have cereal & milk? Would she eat at all? What could be kept without refrigeration? When we focus on this eating style and macro choices, we find a diet perfectly fit for us. Designed by us over our evolution. Notice the difference in the way you feel eating fats.