Dietary Therapies for Epilepsy

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What is the Ketogenic Diet?

The ketogenic diet is a recognised and proven therapy for epilepsy since the 1920’s. It is an important alternative treatment for people with medication resistant epilepsy that are not epilepsy surgery candidates.

The ketogenic diet has primarily been used in children with poorly controlled seizures but can be used for any age group. It’s standard treatment with certain epilepsy syndromes, and can help reduce seizures in two out of three children and may prevent seizures completely in one out of three.

Essentially about half the children who follow the Ketogenic Diet have a significant drop in seizures with some having seizures stop completely.

It is a strict diet high in fats and low in carbohydrates. This makes the body burn fat for energy instead of glucose – mimicking a fasting state, which causes process called ketosis.

Distribution of fats, carbs and proteins

No single mechanism is likely to explain the antiseizure effects of the ketogenic diet, but they are mostly related to complex metabolic changes in the body associated with the diet. It is a form of treatment that, like other therapies for epilepsy, has side effects that have to be watched for.

The classic ketogenic diet is rigid, individually calculated, and medically monitored. Supplements must be taken to provide adequate vitamins and minerals. It takes a strong commitment from the whole family.


Following the ketogenic diet requires a team approach – including doctors, nurses, and especially dietitians specifically trained in the management of people on this diet.

How the diet affects the body

Our bodies usually run on energy which we get from glucose in food. Our body can’t store large amounts of glucose, and we only have about one days supply.

Sometimes the ketogenic diet is started with a period of fasting, so our body uses up any stored glucose. What happens then is the body begins to run on energy from our fat supplies. When our body burns fat, it creates molecules called ketones. Scientists have understood that these molecules somehow cause a change in metabolism leading to a strong anticonvulsant effect.

The ketogenic diet keeps this process going. It forces the body to burn fat for energy.

There is also some suggestion that changes in gut microbiota and anti-inflammatory effects whilst on this diet are also important in reducing seizures.

The diet provides most (80 percent) of its energy from fat. The rest comes from carbohydrates and protein. Each meal has about four times as much fat as protein or carbohydrate.

Who is the diet for?

The ketogenic diet is predominantly used in children with poorly controlled seizures (but can be used in adults). The diet may help to reduce the number or severity of seizures and can often have positive effects on behaviour.

Starting the diet

This process may differ in different institutions. The diet is usually started under close medical supervision in the hospital. It begins gradually and is increased to the full amount over a 3 to 4 day period. During this time blood sugar and ketone levels are monitored. Some hospitals may use a fasting period.

More specific information can be found at the Children’s Epilepsy Program

How soon does it to work?

It is difficult to predict. The diet may become effective immediately or can take several months. Each child is unique and has different seizure patterns and frequency. However, there is usually some improvement within the first few weeks on the diet. Improvement in behaviour will be also seen in some children.

Will medications be stopped?

Medications will continue as normal unless changed by the neurologist. There may be a review of the medications if the diet is successful in controlling the seizures.

Are there any side-effects?

The diet is not without side effects. Gastrointestinal complaints are most common and include constipation and worsening of reflux, diarrhoea and abdominal cramps. Weight loss or gain may also occur. Speak to your doctor about various side effects of this diet.

Vitamin supplementation

The diet alone is inadequate in many vitamins and minerals. Supplements will be prescribed for your child while on the ketogenic diet.

Discontinuing the diet

Children for whom the diet has been effective usually stay on the diet for about two years.  The diet may also be discontinued if the side effects are intolerable, the family does not feel that the diet is worth the effort, or it is difficult to maintain.

Like discontinuing medications, the diet must be gradually weaned with the supervision of your doctor and dietitian. Some children remain seizure free after transitioning back to a regular diet.

Other diets

Regardless of the effectiveness of the classic ketogenic diet, many people discontinue it because of its unpalatable and restrictive features. There is no question that the classic ketogenic diet can be difficult to follow, or you may want to transition to a less structured diet.

In the last 20 years, new variants of the ketogenic diet have emerged, including the Modified Atkins diet (MAD), the low-glycaemic-index diet, which although it has a high fat content, allow more protein and does not restrict calories and fluids. Several studies have shown that these new variants of the ketogenic diet have a similar efficacy to the classic ketogenic diet (Miera et al 2019)

The Modified Atkins Diet (MAD)

Is a less restrictive variation of the ketogenic diet and can be started at home without a fast. There is unlimited protein and fat intake, and does not restrict calories or fluids.

The Low-Glycemic Index (Low GI) treatment diet

Does not necessarily cause ketosis, and may instead reduce seizures by lowering glucose levels in the blood and possibly in brain cells.

While still restrictive compared to a “normal” diet, these diets are easier to incorporate into normal life and easier to follow when eating out. The scientific evidence for their effectiveness is still in early stages and varies greatly between studies.

Speak to your neurologist if you want any further information about dietary therapies for epilepsy.

Further information:

EAA Videos – Dr Andrew Bleasel – Diet Therapies for Epilepsy

Factsheet – Ketogenic Diet

The Charlie Foundation – Set up by Charlies parents whose seizures were successfully controlled by the diet.

Diet therapies for epilepsy 

Ketogenic Diet Resource, includes recipes