Once again it’s time for another mailbag.
Mixed Brain Fuel
Question: On a ketogenic diet, how rapidly does the brain flip between glucose and ketones for fuel? Can it use both fuel sources simultaneously?
Answer: The above question sort of encompasses a few different potential things and I’m not 100% sure which you’re asking so I’ll just cover them all. First realize that one fuel that the brain cannot use is fatty acids, at least not directly. This has led to the oft-stated belief that the brain can only use glucose. But this is incorrect as the brain has an alternative fat derived fuel which are ketones (or ketone bodies, the two major of which are beta-hydroxybutyrate and acetyl-acetate).
Ketones are produced primarily in the liver (from the breakdown of fatty acids) and exist predominantly as an alternative fuel source for the brain (they can also be used by skeletal muscle) during periods of low-carbohydrate availability. … Keep Reading