The ketogenic diet is a very low-carb, high-fat diet.It involves drastically reducing carbohydrate intake and replacing it with fat. This reduction in carbs puts your body into a metabolic state called ketosis. When this happens, your body becomes incredibly efficient at burning fat for energy. It also turns fat into ketones in the liver, which can supply energy for the brain. It lowers blood sugar and insulin levels, and shifts the body’s metabolism away from carbs and towards fat and ketones.