Authored By: Eric Kossoff MD on 10/2017
Reviewed By: Joseph I. Sirven MD on Wednesday, October 25, 2017

What is the ketogenic diet?

The "classic" ketogenic diet is a special high-fat, low-carbohydrate diet that helps to control seizures in some people with epilepsy. It is prescribed by a physician and carefully monitored by a dietitian. It is usually used in children with seizures that do not respond to medications. It is stricter than the modified Atkins diet, requiring careful measurements of calories, fluids, and proteins. Foods are weighed and measured.

  • The name ketogenic means that it produces ketones in the body. (keto = ketone; genic = producing) Ketones are formed when the body uses fat for its source of energy.
  • Usually the body uses carbohydrates (such as sugar, bread, pasta) for its fuel. Because the ketogenic diet is very low in carbohydrates, fats become the primary fuel instead. The body can work very well on ketones (and fats).
  • Ketones are not dangerous. They can be detected in the urine, blood, and breath. Ketones are one of the more likely mechanisms of action of the diet, with higher ketone levels often leading to improved seizure control. However, there are many other theories for why the diet will work.

Who will it help?

  • Doctors usually recommend the ketogenic diet for children whose seizures have not responded to several different seizure medicines.
  • The classic diet is usually not recommended for adults, mostly because the restricted food choices make it hard to follow. However, the modified Atkins diet does work well. This also should be done with a good team of adult neurologists and dietitians.
    • Find more information about adults and diets.
    • Read an article about results from a large adult epilepsy diet center.
  • The ketogenic diet has been shown in many studies to be particularly helpful for some epilepsy conditions. These include infantile spasms, Rett syndrome, tuberous sclerosis complex, Dravet syndrome, Doose syndrome, and GLUT-1 deficiency. Using a formula-only ketogenic diet for infants and gastrostomy-tube fed children may lead to better compliance and possibly even improved efficacy.
  • Recent studies have also shown that infants can be successfully started on dietary therapy too.
    • Read an article about the ketogenic diet for neonates.
    • Learn about Ketogenic Guidelines for Infants.
  • The diet works well for children with focal seizures, but may be less likely to lead to an immediate seizure-free result.
  • In general, the diet can always be considered as long as there are no clear metabolic or mitochondrial reasons not to use it.
  • The diet is sometimes started to help reduce or even stop anti-seizure drugs. However, that does not always occur – often it is a “partnership” between drugs and food to help reduce seizures that works.

What is it like?

  • The typical "classical" ketogenic diet, called the "long-chain triglyceride diet," provides 3 to 4 grams of fat for every 1 gram of carbohydrate and protein. That is about 90% of calories from fat.
  • Usually when the classic ketogenic diet is prescribed, the total calories are matched to the number of calories the person needs. For example, if a child is eating a 1500 calorie regular diet, it would be changed to a 1500 calorie ketogenic diet. For very young children only, the diet may be prescribed based on weight, for example 75 to 100 calories for each kilogram (2.2 pounds) of body weight. If it sounds complicated, it is! That’s why people need a dietician’s help when using this diet.
  • A ketogenic diet "ratio" is the ratio of fat to carbohydrate and protein grams combined.
    • A 4:1 ratio is more strict than a 3:1 ratio and is typically used for most children.
    • A 3:1 ratio is typically used for infants, adolescents, and children who require higher amounts of protein or carbohydrate for some other reason.
  • The kinds of foods that provide fat for the ketogenic diet are butter, heavy whipping cream, mayonnaise, and oils (e.g., canola or olive).
  • Because the amount of carbohydrate and protein in the diet have to be restricted, it is very important to prepare meals carefully.
  • No other sources of carbohydrates can be eaten.
  • The ketogenic diet is supervised by
    • a dietician who monitors the child's nutrition and can teach parents and the child what can and cannot be eaten
    • a neurologist who monitors medications and overall benefits