The brain likes keto because of betahydroxybutyrate, though it's the only organ to require glucose (not a problem in keto as we have gluconeogenesis from fat and proteins)

You know what likes keto even more? Your heart. There are studies and research of fatty acids being able to reverse heart disease, and them being incredibly more efficient fuels than glucose is. N=1 placebo, but I certainly feel my heart (in an overweight body) pumping better and with less effort 1+ weeks into very low carb.

Adaptation takes a while because our mitochondria are dysfunctional due to standard diets being so high in glucose. Fatty acids are the better fuel for muscles, and mitochondria in general.