What is the Ketogenic Diet Therapy?


A ketogenic diet is a high fat, low carbohydrate and adequate protein diet that is used in people with uncontrolled drug resistant epilepsy to help reduce seizures. The ketogenic diet therapy for drug resistant epilepsy should be supervised by a healthcare professional.

The ketogenic diet is designed to force the body to use fat as an energy source instead of glucose. When fat is broken down for energy it produces compounds known as ketones. These ketones are thought to exert an anti-epileptic effect in the brain.

The diet has been used for nearly 100 years and has been shown to be effective in half of children who trial the diet.1

Other potential benefits of ketogenic diet therapy (KDT) - in addition to possible reduction in seizures - may include2:

  • Potential reduction of drugs and their side effects
  • Increased alertness
  • Increased energy levels
  • Increased feeling of wellbeing

Watch Chloe’s Story and find out how Ketogenic Diet Therapy has helped her manage her epilepsy

Discover more real life ketogenic diet stories here: Your Ketogenic Stories

There are three different versions of ketogenic diet commonly used in ketogenic dietary therapy for drug resistant epilepsy. In all of them the intake of carbohydrates is restricted, with rich intake of fats and sufficient consumption of protein to support growth and development. All versions of the ketogenic diet have been showed to be effective in significantly reducing seizures in in approximately half of the children who start ketogenic dietary therapy.2

Classical Ketogenic Diet (CKD)

First documented in the 1920’s, the Classical Ketogenic Diet is based on a ratio of fat to protein and carbohydrate. In this high-fat diet, fat often provides between 80% to 90% of total number of calories consumed. The remaining 10%-20% of calories come from carbohydrates and protein combined. 

The exact ratio of fat to protein and carbohydrate is tailored to individual needs by the dietitian depending on level of ketosis, seizure management and protein requirement.

The Classical Ketogenic Diet is lower in protein than the regular diet, but provides sufficient protein to satisfy the body’s growth requirements. 

On this diet, everything that is eaten is weighed.

Modified Ketogenic Diet (MKD)

The Modified Ketogenic Diet is based on the same principle as the Atkins Diet for weight loss, but without the deficit of calories consumed. The balance of calories is maintained by the addition of fat to the diet. This version of ketogenic diet focuses a lot on restricting the intake of carbohydrate while allowing protein foods to be eaten more liberally. Because of its flexibility on protein consumption, the Modified Ketogenic Diet is a popular choice for older children and adults. This diet requires less preparation and planning and fits more easily with an independent lifestyle.

With this diet, carbohydrate intake is restricted to 10 – 30g per day, with no limits imposed on protein and fat consumption, or total calorie consumption. 

Carbohydrates are weighed and high fat foods are provided in household measures (e.g. 1 tbsp of double cream). Protein foods do not need to be weighed.

Medium Chain Triglyceride (MCT) diet

Medium chain triglycerides are fats which are easily metabolised into ketones by the body. 

MCT ketogenic diets allow a higher quantity of carbohydrate and protein to be included in the daily diet. The diet contains some fat naturally found in foods as well as supplementation with MCT fat. 

School age children manage MCT supplements well and enjoy the flexibility of the additional carbohydrate allowance.

With MCT diets, 75% of the daily calorie intake comes from fat with around 45% of the fat provided as MCT fat. The remaining calories are provided by carbohydrates and protein.

Everything that is eaten on this diet is weighted.

  • Epilepsy is the most common serious brain disorder worldwide3
  • More than three in ten epilepsy patients become resistant to anti-epileptic drug treatment3,4
  • Studies showed that the ketogenic diet significantly reduced the number of seizures in a proportion of children who did not respond to anti-seizure medicines. A clinical trial at Great Ormond Street Hospital showed that after three months, around 4 in 10 (38%) children who started the diet showed a more than half reduction in seizures, and were able to reduce their medication. Although not all children had better seizure control, some had other benefits such as increased alertness, awareness and responsiveness.5
  • Studies looking at the effectiveness of the modified ketogenic diet show a seizure reduction of up to 60%6
Toddler sharing a cup of milk with her mum

Carbohydrates are found in foods like bread, pasta, potato, rice, fruit and vegetables.7 The body breaks carbohydrates down into glucose in order to provide energy. In the ketogenic diet, however, fat is used as the body’s primary energy source instead.

“The ketogenic diet is built around having low carbohydrates, low protein and high fat content,” Derek Clarke, Nutricia Ketogenic and Metabolic Chef explains. “So, as a chef, it’s a case of choosing ingredients that adhere to those criteria. Different patients are also on different ratios of fat to carbs/protein; some are on four to one, three to one and two to one, which can make certain recipes more acceptable than others.”

He continues: “For example, once fat powders became available, there was no longer a need to use large quantities of oil to increase fat content, and it became possible to make food that was a lot less greasy. Instead of using wheat flour, fibre flour, coconut flour or ground almonds are all great and tasty alternatives. Fibre flour is particularly good for making low carb bread, while celeriac, swede and parsnips are perfect substitutes for potato.

“As we can’t use sugar, a lot of my recipes involve sweeteners. At the same time, berries are a great go-to natural sweetener - it’s always handy to have raspberries and blueberries in the fridge because they’re a good start to any recipe.”

Fat is found in foods like avocado, oils, cream, butter and mayonnaise.7 Foods high in fat are an essential part of the ketogenic diet and will provide the majority of calories that the body needs, as fat is the primary source of energy on the ketogenic diet. Fat creates energy when it is broken down by the body to make ketones. Ketosis is a natural state the body finds itself in when it is using fat as its main fuel instead of glucose.

Protein is found in meat, chicken, fish, eggs, nuts and legumes.7 It is important for children’s growth and is used to build and repair tissue in the body. Protein is especially important for bones and muscles. Our protein needs change across our lifetime. Children’s protein needs range from 12.5 g/day for babies under 3 months of age to around 28 g/day for 10 year old children, depending on age and body weight among others.  Adults in the UK are advised to eat 0.75g of protein for each kilogram of body weight, based on the Reference Nutrient Intake (RNI).7 Your dietitian will advise you on your / your child’s recommended protein intake.

In the Classical Ketogenic Diet, the intake of protein is restricted, but the diet provides sufficient quantities of protein to cover the body’s needs. In the Modified Ketogenic Diet, protein intake is unrestricted.

The day-to-day management of KDT involves the provision of a diet that is restricted in carbohydrate and sugar content, high in fat, and containing enough protein to meet the requirements to build and repair the body. 

Alongside food meeting the specific requirements laid out above, children undergoing KDT also require a suitable vitamin and mineral supplement as well as their ongoing anti-epileptic medicines.

Brother and sister cooking in the kitchen

Chef Derek explains: “My advice to parents interested in the ketogenic diet is to do as much research and gain as much knowledge about it as you can. Before you start the diet, it’s a good idea to make some of the ketogenic recipes and give it to your child to see if they like it, because it’s a big change from a normal diet. There are also lots of great places to find new recipes and inspiration, including our recipes books, our Chef’s Corner here on the Nutricia website and of course our social media channel Nutricia KetoConnect on Facebook and Instagram.”

A clinical trial at Great Ormond Street Hospital in 2008, and other studies since then, showed that in just 3 months the diet significantly reduced the number of seizures in a proportion of children whose seizures did not respond well to anti-seizure medicines. After three months, around 4 in 10 (38%) children who started the diet had the number of their seizures reduced by over half and were able to reduce their medication. Also, some of the children had other benefits like increased alertness, awareness and responsiveness.5

Following KDT brings a significant lifestyle change and constitutes a steep learning curve. Understandably, many families and adult patients need considerable support, especially during the first few weeks. However, with the right information and support, the experience of Ketogenic Dietary Therapy can be a positive journey. For example, batch cooking, meal planning, preparing snacks in advance and generating new recipe ideas can all be really helpful. Sometimes on balance, the benefits may not outweigh the limitations of following a restrictive diet for everyone.

Around 3 months after starting the diet, your ketogenic team will do a follow-up assessment to evaluate whether the diet is still the most appropriate treatment option2. By this time, your ketogenic team will be able to assess the diet’s effectiveness in controlling or reducing seizures in your or your child’s case.

When people first start the diet, they may experience feelings of tiredness, irritability or generally feel unwell for a few days. This is temporary.

Other side effects when the diet is continued long term may include5:

  • Constipation
  • Reflux
  • Raised blood triglycerides and cholesterol levels
  • Kidney stones
  • Very rarely pancreatitis

During any period of illness, you should make sure to follow advice from your GP, local paediatrician and neurologist, and also contact your dietitian or epilepsy nurse specialist for any further advice.

If any new medications are prescribed, you should make a request for the reduced carbohydrate preparation, although one may not always be available. You may also be asked to measure your/ your child’s blood glucose levels.

You should always maintain regular contact with your ketogenic team and speak to your dietitian or nurse specialist about the recommended frequency for testing ketone and glucose levels. Once patients are well established on the diet, they may be able to reduce the frequency of testing; your ketogenic team will advise you accordingly.

Here’s a handy list of the things you need to keep on top of while following ketogenic diet therapy:

  • Make sure you have all the relevant products prescribed from your GP before starting the diet.
  • If you/ your child start the diet in hospital, make sure you have a supply of relevant products to go home with.
  • Carefully follow the recipes provided by your dietitian, using weighing scales where indicated.
  • Remember to measure ketones as instructed by the ketogenic team.
  • Record seizures and ketones in your daily seizure record chart.
  • Regularly update your ketogenic team.
Brother and sister cooking in the kitchen

Moving onto the ketogenic diet can be a big change for you / your child and your family, but there is a good chance that it will be extremely beneficial - half of children who trial the diet will experience a 50% reduction in seizures.1

There is often an assumption that the ketogenic diet can taste bland, but this doesn’t have to be the case; your dietitian can provide you with access to new recipe ideas when you need them, and help you see how the ketogenic diet can still taste good. Further to this, there are regular cookery days and events that you can attend throughout the year to get new ideas and inspiration for the diet. 

Brother and sister cooking in the kitchen

“When a new ingredient or product comes along it can open up a lot more possibilities with the recipes,” Derek says, “Like all diets, everyone just wants some inspiration and that’s why I’m constantly experimenting with new ingredients to try and develop new and exciting recipes.” 

Part of Derek’s role at Nutricia is to consistently look at new ways to innovate the ketogenic diet in order to push the boundaries of what is possible from a flavour perspective.

He says: “My background is as a baker, so flour is a huge part of that - but obviously we can’t use flour in the ketogenic diet. Fortunately, there are a lot of substitutes like fibre flour, ground almonds and coconut flour - it’s just a case of trying to blend the ingredients in the right way for the best outcome. When you’re making a cupcake, for example, you want it to taste and look exactly like a normal cupcake, so certain recipes are trickier than others and there can be some experimentation involved!”

A few things to remember that will help make your/your child’s KDT go all the smoother:

  • Ensure that you always have a good supply of your special dietary products and that they are in date.
  • Your special dietary products are prescribed by your GP. These are obtained via a pharmacy or home delivery.
  • Medications to control epilepsy should be given as directed by your neurologist – always keep supplies available and change to tablets and reduced carbohydrate preparations as soon as possible.
  • Keep a spare set of batteries for weighing scales at home so that you never run out.
Ketogenic Diet therapy food
  • Once you / your child is established on the diet, consider batch cooking and then freezing favourite meals to save time.
  • For children, a copy of your child’s feeding plan can be sent to your child’s nursery or school. Your dietitian and nurse specialist can speak to your child’s school about ketone testing and managing high or low levels.
  • Ask your child’s school to let you know about special occasions in advance. You can then prepare ketogenic diet friendly celebratory snacks so that your child can join in on the celebrations. 

There is a lot of focus on the ketogenic diet and seizure reduction, but the ketogenic diet can have a large impact on QoL too. A recent survey looking at parent and patient views of antiepileptic drugs and ketogenic diet (KD) experience revealed the below results8:

  • 53% reported that the KD had very few side effects compared with antiepileptic drugs
  • 51% felt more involved in their child’s health since starting KDT
  • 49% reported that the ketogenic diet had improved their child's quality of life 
  • 45% wish that they had known about the ketogenic diet sooner 

Nutricia have a range of resources to support a Ketogenic Diet, explore our website and speak to your HCP to find out more.

After around 2 years on ketogenic diet therapy for drug resistant epilepsy, your ketogenic team will assess whether it is time to wean you or your child off the diet. This will be done in a controlled way, under the strict supervision of the ketogenic team.

Hayley Greeff

Hayley Greeff

Hayley is a Registered Dietitian working within the Metabolics and Ketogenics Medical Affairs team at Nutricia. Hayley has worked in acute and community settings across the NHS, where she had first-hand experience working with a range of medical conditions.


  1. Cross, J. H. and Neal, E. G. (2008), The ketogenic diet – update on recent clinical trials. Epilepsia, Vol , Issue S8, pages 6-10,  The ketogenic diet—update on recent clinical trials - Cross - 2008 - Epilepsia - Wiley Online Library
  2. Ketogenic diet: overview | Great Ormond Street Hospital (gosh.nhs.uk) - https://www.gosh.nhs.uk/conditions-and-treatments/procedures-and-treatments/ketogenic-diet/  - Accessed in Feb 2024
  3. World Health Organisation website, https://www.who.int/health-topics/epilepsy#tab=tab_2 - Accessed Feb 2024
  4. Epilepsy Society website, https://epilepsysociety.org.uk/about-epilepsy/drug-resistant-epilepsy  - Accessed Feb 2024
  5. Epilepsy Society website, Ketogenic Diet section -  https://epilepsysociety.org.uk/about-epilepsy/treatment/ketogenic-diet - Accessed Feb 2024
  6. Martin K et al. Cochrane Database of Systematic Reviews 2016:CD001903.pub3 - https://pubmed.ncbi.nlm.nih.gov/26859528/
  7. British Nutrition Foundation website accessed in Feb 2024 - https://www.nutrition.org.uk/
  8. Neurodigest, Issue 4, winter 2018, page 16, https://neurodigest.co.uk/our-journal/

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