The Effects of Lactate and Ketones on the Brain

The body tries to make glucose or at least glucose substrates from non-carbohydrate sources like fatty acids and amino acids. In doing so, it tends to back up at a part called acetyl-cola. This is an intermediary in the glycolytic pathway that produces ATP. The brain can use ketones but doesn't want to use fatty acids for energy. Do you know why? Why has the brain not evolved?"