Comment by rwyinuse

"for millions of years we were constantly fasting, then we hunted and killed animals, eating their protein and fat, no carbs, we were constantly in ketosis"

Those hunter-gatherers of the past certainly did eat whatever carbs they could find - wild roots, tubers etc. Gathering plant-based food was easier than hunting. Most Westerners today eat way too much meat, so I wouldn't recommend replacing carbs with that.