Beta-hydroxybutyrate floats around in your blood, and importantly, can cross different important barriers to be able to be turned into energy at all times. One of the most important areas where this happens is in the brain. The blood-brain barrier (BBB) is usually a very tightly regulated interface, but since BHB is such a rock star and so hydrophilic, your brain knows to let it in so it can bring energy to the party at any time. This is one of the main reasons why increased BHB levels lead to heightened mental acuity.*