everyone is entitled to their own beliefs, but not their own facts. Glycogen is the preferred fuel, which are giant chains of glucose (carb) molecules. I've done keto, and you have to be very careful as even a small amount of carbs will quickly shift the body out of ketosis and back into using glycogen. Doesn't the fact that ketosis is so fragile indicate to you that it's not the preferred state? Homeostasis reigns, and the body gets away from ketosis whenever it can. It's an extreme state.