When I ask the same question it says primarily glucose and also mentions ketone bodies. It mentions that the brain is flexible and while it normally metabolizes

When I ask the same question it says primarily glucose and also mentions ketone bodies. It mentions that the brain is flexible and while it normally metabolizes glucose it may sometimes need to metabolize other things. This is both at gemini.google.com and using google.com in "AI mode" in private browsing. gemini.google.com mentions lactate and fat. But it also knows I care about science. I'm not sure how much history is used currently. But this is kind of silly because if you're a member of the public and ask a scientist what the brain uses as fuel they'll also say glucose. If you've ever been in a conversation with someone who felt the need to tell you *every detail* of everything they know, then you'll understand that that's not how human communication typically works. So if you want something more specific you have to start the conversation in a way that elicits it.