The liver additionally produces glucose from non-carbohydrate sources other than fatty acids by a process called gluconeogenesis during starvation. In the brain, ketone bodies are a vital source of energy during fasting or strenuous exercise. Although termed bodies, they are molecules, not particles.The three endogenous ketone bodies are acetone, acetoacetic acid, and beta-hydroxybutyric acid.Other ketone bodies like beta-ketopentanoate and beta-hydroxypentanoate may be created as a result of the metabolism of synthetic triglycerides, such as triheptanoin.he liver additionally produces glucose from non-carbohydrate sources other than fatty acids by a process called gluconeogenesis during starvation. In the brain, ketone bodies are a vital source of energy during fasting or strenuous exercise. Although termed bodies, they are molecules, not particles.