The ketogenic diet is a high-fat content diet in which carbohydrates are nearly eliminated so that the body has minimal dietary sources of glucose. After depleting carbs consumed in food, the body metabolizes body fat, converting it to glucose — which is the true fuel of the body and especially the brain. However the metabolized fat also produces ketones, which are the most efficient fuel for the body and brain. The ketogenic diet has been in clinical use for over 80 years, primarily for the symptomatic treatment of epilepsy.