Betahydroxybuterate is a by-product produced by the liver during the process of fat metabolism. The liver makes betahydroxybuterate during periods of fasting, starvation, or prolonged physical exertion, or when an individual's epilepsy treatment involves a high-fat dietary therapy such as the ketogenic diet. It is theorized that betahydroxybuterate and acetoacetate (known as ketones or ketone bodies) may accumulate in the brain and be an important factor in seizure control associated with dietary therapies.