MCT diet This diet includes some fat that occurs naturally in food, as well as some from a supplement of medium chain triglycerides (MCT) fat. This supplement can be mixed into food or milk and is only available on prescription. When the MCT is broken down for energy it produces more ketones and as a result more carbohydrate is allowed than on other ketogenic diets. This diet is used for all children and can be helpful in school age children as the slightly increased carbohydrate allowance means they can include some familiar foods. The MCT diet contains: 75% to 90% fat (30%-60% MCT) 10% protein 10% to 15% carbohydrate.