A low carb ketogenic diet is one where you cut out or extremely limit your carbohydrate intake, which thrusts your body into a process called ketosis. When you cut the carbs out of your diet your body switches its energy source from carbohydrates (glucose) to an energy source called ketones, which is what your body will start to produce with the absence of carbohydrates (glucose) in the body. To break down your calories, your fats should make up 75% of your total caloric intake, protein should be at 20%, and carbs at 5%. Fitness enthusiasts like a low carb ketogenic diet because it forces the body to adapt and more efficiently use fat as fuel. The reduction of carbs causes a rise in ketones, which stem from liver fatty acids and are used for energy since carbs are sparse. It's been noted that ultra-endurance athletes who followed a low carb ketogenic diet burned up to 2.3 times more fat in a 3-hour exercise session.