"The basis of the ketogenic diet is the brain's ability to utilize ketones as an energy source. Ketones include b-hydroxybutyrate, acetoacetate, and acetone, which are products of fat breakdown. Under normal conditions, the brain derives most of its energy from glucose. Under fasting conditions, hormonal changes cause fat cells to release fats, which are then broken down in the liver. The liver packages the energy contained in fat into ketones. The liver releases ketones into the blood, which then transports them to the brain." (Department of Neurology, Washington University School of Medicine, http://neuro.wustl.edu/patientcare/clinicalservices/pediatri...).