What “keto” means Ketosis The “keto” in a ketogenic diet comes from the fact that it allows the body to produce small fuel molecules called “ketones”.2 This is an alternative fuel source for the body, used when blood sugar (glucose) is in short supply. Ketones are produced if you eat very few carbs (that are quickly broken down into blood sugar) and only moderate amounts of protein (excess protein can also be converted to blood sugar). The liver produces ketones from fat. These ketones then serve as a fuel source throughout the body, especially for the brain. The brain is a hungry organ that consumes lots of energy every day, and it can’t run on fat directly. It can only run on glucose… or ketones.