What is the ketogenic diet?

The ketogenic diet is a high-fat, low-carbohydrate, adequate-protein, medical dietary therapy. The ketogenic diet is used to control seizures in patients with epilepsy that does not respond to anti-epileptic drugs, which is sometimes called “drug resistant epilepsy” or “refractory epilepsy”. The ketogenic diet may also be considered for patients who experience significant side effects from their anti-epileptic drugs.

The ketogenic diet is a precise and carefully calculated medical diet, which requires monitoring under the supervision of an experienced ketogenic diet team, usually consisting of a Neurologist, Dietitian and Nurse.

How effective is the ketogenic diet?

Research shows that just over half of children on the ketogenic diet will have 50% or more improvement in seizures. About one third of children will have over 90% improvement in seizures and about 10-15% will become seizure-free. When dietary therapy is effective in controlling seizures, anti-epileptic drugs can sometimes be reduced or even stopped. Many parents also report improved development and behaviour.

The efficacy of the ketogenic diet seems to remain with time, and many children continue to have seizure control even after the ketogenic diet is stopped.

Despite the promising response rates observed in children treated with the ketogenic diet, there are limited studies in adults. Efficacy rates of the ketogenic diet are slightly lower in adults, but are still considered comparable to the effectiveness rates of children. Studies show 30-40% of adults will have 50% or more improvement in seizures at 3 months, although fewer than 10% will have 90% improvement in seizure reduction or seizure freedom.

What type of seizures can the ketogenic diet help to manage?

The ketogenic diet is effective in several types of epilepsy syndromes and situations. However, research suggests that the ketogenic diet may be particularly beneficial for people with:

  • Glucose transporter protein I (GLUT-I deficiency)
  • Pyruvate dehydrogenase (PDH) deficiency
  • Myoclonic-astatic epilepsy (Doose syndrome)
  • Tuberous sclerosis complex
  • Rett syndrome
  • Severe myoclonic epilepsy of infancy (Dravet syndrome)
  • Lennox-Gastaut syndrome
  • Infantile spasms (West syndrome)
  • Children receiving a formula only ketogenic diet

Several new epilepsy conditions have recently shown benefit with the ketogenic diet, including refractory status epilepticus, FIRES (fever-induced refractory epilepsy syndrome), childhood absence epilepsy and Sturge-Weber syndrome.

How does the ketogenic diet work?

The body is designed to use carbohydrate (glucose) as the preferred energy source. The ketogenic diet works by shifting the body’s metabolism to use fat as the primary energy source, instead of glucose. When the body is in a fat-burning metabolic state, this results in the production of ketone bodies, which accumulates in the blood. When ketone bodies accumulate in the blood to high enough levels, the body enters into a metabolic state of “ketosis”, which results from the shift from carbohydrate to fat metabolism as the main energy source. Ketone bodies are considered the hallmark of the ketogenic diet.

The high level of ketone bodies seen in a person on the ketogenic diet is associated with better seizure control; however the exact mechanism involved remains unknown.

What is a ‘ketogenic ratio’?

The ketogenic ratio refers to the ratio of the grams of fat, compared to the grams of protein and carbohydrate in the diet. The healthcare professional determines which ketogenic ratio is most appropriate for each patient.

The Classical ketogenic diet is usually a 4:1 ratio, which means for every 4g (grams) of fat, there is 1g (gram) of carbohydrate and protein combined. In some patients, such as infants and young children, a lower ketogenic ratio such as a 3:1 ratio may be preferred, to allow for slightly more protein to be consumed, supporting growth and development.

While on the ketogenic diet, can anti-epileptic drugs be reduced or stopped?

Your healthcare professional is best placed to determine whether your anti-epileptic drugs can be reduced or stopped while on the ketogenic diet. Generally this may be based on how well a person responds to the ketogenic diet. Interestingly, some anti-epileptic drugs may respond better with the ketogenic diet. Therefore your healthcare professional is the best person to answer this question.

How long does it take for the ketogenic diet to be effective?

This can vary from person to person based on individual epilepsy syndromes, seizure patterns and frequency. For some people, the ketogenic diet can be effective immediately, and for others, it can take several months. Studies show the diet should be trialled for a minimum of 3 months. It is important to discuss this with your healthcare professional, to ensure you manage your own expectations and to trial the diet for an adequate length of time before deciding the come off the diet.

How long do people usually stay on the ketogenic diet?

In cases when the ketogenic diet is effective, it is generally used for at least 2 years. After this time, your healthcare professional may recommend coming off the diet. The efficacy of the ketogenic diet seems to remain with time, and many children continue to have seizure control even after the ketogenic diet is stopped.

Are there any side effects of the ketogenic diet?

Similar with most medical treatments, the ketogenic diet may cause side effects, which is why the ketogenic diet requires monitoring by a healthcare professional.

The most commonly reported side effects are gastrointestinal disturbances such as constipation, nausea, vomiting, or diarrhoea. Consult with your healthcare professional to learn more about potential side effects.


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