From Merriam Webster

A diet that supplies large amounts of fats, moderate amounts of proteins, and minimal amounts of carbohydrates and that is undertaken for weight loss or to control seizures in treatment-resistant epilepsy Note: As the body is deprived of carbohydrates in the ketogenic diet, insulin secretion drops and glycogen stores in the body become depleted. The body then enters a state of nutritional ketosis where ketone bodies formed by the metabolism of fatty acids replace glucose as the primary energy source.