Originally, the ketogenic diet was used to help treat epilepsy in children, because the way the brain uses the fuel from a high fat diet.
Essentially the ketogenic diet, also called keto, is a diet that is high in fat, has moderate protein and is very low carb. Normally carbohydrates are digested and they are turned into glucose. This glucose is important to fuel your brain.
On the keto diet, you consume very few carbohydrates, usually fewer than 20 grams a day. Instead of using glucose to fuel your brain, your liver changes the fat into fatty acids and ketone bodies. Your brain can function on this sort of “fuel” as well.
Traditionally, it is hard to lose weight because your body must first use all the glucose in your system before it starts burning your stored fats as fuel. Keto expedites this process by only supplying your body with fats. Once your body begins to use fat as its primary fuel source it will start using the fat that is stored on your body as well.