What's involved in the Ketogenic diet?

Overview

The ketogenic diet is a carefully calculated, medically managed diet, designed to mimic a fasting state over a long period of time.

It is available as a treatment option for children with difficult-to-control epilepsy and some neuro-metabolic disorders.

The idea of using diet to help manage seizures is not new.  In fact, Physicians in Ancient Greece treated epilepsy by altering the patient’s diet.

In keeping with this ancient approach to treating epilepsy, the Ketogenic Diet was originally developed in the 1920’s to manage difficult-to-control seizures.1 There were hardly any effective medications at the time, and the diet was developed to “simulate the apparent anticonvulsant effects of fasting”.2  While it remained a popular treatment during the 1920’s to 1940’s, it fell out of favour during the 1950’s with the development of anti-epileptic drugs (AEDs).

When on the Ketogenic Diet, a simulated ‘fasting state’ is achieved by switching the body to burn fats rather than carbohydrates. When there is very little dietary carbohydrate, the liver converts fat into fatty acids and ketone bodies. The ketone bodies then pass into the brain, replacing glucose as the primary energy source. This elevated level of ketone bodies in the blood is referred to as ketosis.

The body burns fat when:

  • The consumption of carbohydrates (e.g. sugars, pasta, and bread) is limited
  • The consumption of foods high in fat (such as butter, cream, and oil) is increased
  • There is adequate consumption of protein to aid body growth and repair

It is important that the ratio of fats to carbohydrates and proteins be medically determined and carefully managed to ensure optimal outcomes and limit untoward side-effects and potentially serious nutritional deficiencies.  Typically a Paediatric Dietician, a Paediatric Neurologist, and an experienced Nurse are involved in the management of patients who are placed on the Ketogenic Diet.

  • 1. Wilder RM. The effect of ketonemia on the course of epilepsy. Mayo Clin Bull. 1921;2:307, cited in Freeman et al. The Efficacy of the Ketogenic Diet. Pediatrics. 1998;102:6.
  • 2. Freeman, Vining, Pillas, Casey, & Kelly. The Efficacy of the Ketogenic Diet-1998: A prospective Evaluation of Intervention in 150 Children. Pediatrics, 1998; p. 1362.

Diet Suitability

If your child has failed on several (up to four) anti-epileptic drugs (i.e. their seizures remain uncontrolled), your child’s treating Neurologist may consider placing them on the Ketogenic Diet as an additional treatment to their AED’s.

Children normally remain on their anticonvulsants while the diet is initiated.

If the diet is successful, your child may have their anticonvulsants gradually reduced under medical supervision as decided by your neurologist / paediatrician.

The procedure for commencing on the Ketogenic Diet may vary slightly across settings.

Initial consultation

The procedure for commencing on the Ketogenic Diet may vary slightly across settings. However, consultation and planning typically follows the following process:

  • Your child’s full medical history will be reviewed and a dietary history will be obtained.
  • Your child will be screened for conditions which may contraindicate commencing on the diet (for example, children who have errors of fat metabolism cannot be placed on the diet).
  • The exact dietary requirements will be determined by the Paediatric Dietician. This will involve calculations of calorie requirements, fluid intake, and the appropriate ketogenic ratio of fat to carbohydrate and protein.
  • Parents and carers will receive education about the diet and the side-effects to look out for, and will receive ongoing support from the treating team.
  • Prior to commencement on the diet, a sample of your child’s blood and urine will be collected and analysed.
  • A baseline 12-lead ECG (heart monitoring) and a baseline EEG (monitoring of the electrical activity of the brain) will also be conducted.

Commencing the diet

The classical Ketogenic Diet is initiated by admission to hospital and generally involves a 4-5 day stay. There are other diets, such as the Modified Atkins Diet which can be initiated in the outpatient setting.

It is very important that all diets are initiated under medical supervision.

  • Your child’s blood glucose level will be checked frequently (i.e. generally every 4 hours via finger prick test for the Classical Ketogenic Diet, or once daily during initiation on the Modified Atkins Diet), to monitor for hypoglycaemia.
  • Further blood tests are usually required on day 3.
  • Your child may feel lethargic and lack energy for some time while they adjust to the diet.

Maintaining the diet

Your child will continue to be monitored regularly on the diet by attending an outpatient clinic (i.e. typically every 3 months in older children, more frequently in infants).

Parents are encouraged to persist with the diet for at least 3 months to determine if seizure freedom or reduction occurs.

Typically, children come off the Ketogenic Diet after around two years. The treating Neurologist will determine when the diet will be discontinued and the method for gradual discontinuation.