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Ketogenic dietary therapy (KDT) - For children who are eating orally and their carers

Patient information A-Z

This leaflet is designed for families with children who have been diagnosed with drug-resistant epilepsy and have been prescribed ketogenic dietary therapy (KDT).

What is ketogenic dietary therapy?

KDT is used to help manage drug-resistant epilepsy. First reported in the 1920s it is a medically supervised high fat diet, which is low in carbohydrate and contains enough protein for growth. The diet is carefully calculated for each individual child dependent on their age, eating preferences and activity levels. The quantity of fat, protein and carbohydrate will be calculated by your dietitian.

When is it used?

KDT is usually used when current drug therapies are not providing sufficient relief of seizures. It is considered as a novel drug intervention.

How successful is it?

When you have been prescribed two or three different anti-epileptic medications, trialling KDT is more likely to give you better seizure control than starting a new medication. Fifty to sixty percent of people will see a good reduction in the number of seizures they have, with ten percent becoming seizure free. Your doctor and dietitian will discuss individual goals with you.

Are there different Ketogenic diets?

There are a number of different types of ketogenic diet. Research has shown that they are all effective in reducing seizures. Your dietitian will discuss the options with you, to help you choose which diet to start. This will depend on likes and dislikes, current meal pattern and your family’s eating patterns.

What are the different types of Ketogenic diets?

Classical diet

These diets are described as a ratio of fat compared to protein and carbohydrate together. You will see these described as 2:1, 3:1 or 4:1 ratios. All meals and snacks are set to a similar ratio and are made to precise recipes.

Medium chain triglyceride (MCT) diet

MCT fat produces ketones very well. MCT fat must be taken with each meal and before bed. This ketogenic diet allows quite generous amounts of carbohydrate compared to the other two diets, however only works if the full MCT doses are taken.

Modified ketogenic diet (MKD)

Similar to the weight loss diet ‘The Atkins Diet’ but with additional fat added to each meal to avoid unintentional weight loss. It does not require any MCT as all of the fat can come from foods.

Are they easy to follow?

Ketogenic diets are very unnatural diets. Every meal has to be made following a detailed food prescription. Every food item in the meal needs to be measured accurately, often using electronic scales. Every meal and snack of every day needs to follow the prescription. If extra foods, particularly those containing carbohydrate are eaten, then this can cause a sudden drop in blood ketone levels. This may result in sudden increase in seizures. Your dietitian will work out recipes and meal plans with you.

There are no pre-prepared ketogenic meals in the supermarket. However, meals can be made in batches at home and then frozen. So you can prepare you own stock of ready to use meals.

There are also some food items available on prescription. Your dietitian will discuss which are suitable for you.

How do I start the diet?

Your dietitian will ask you to fill out a food diary for four days. This provides essential information about your energy intake, likes and dislikes, and your meal pattern.

You may be admitted to hospital to start therapy slowly over three days. However, older children are usually safe to start the diet slowly at home over 7 to 10 days. Training on how to prepare meals, create recipes and how to monitor ketones and blood sugars will be provided during your hospital stay or be taught before you seek to start the therapy at home.

Will I need any special kitchen equipment?

You will need electronic kitchen scales that weigh to one gram accuracy. Silicon baking sheets and silicon spatulas are also very useful when preparing meals.

What can I eat on the diet?

Typically, you will have four small meals a day, or three meals and two snacks. The timings of these will be discussed with you by your dietitian. Meals are made using standard foods and special dietary products. Any special dietary products will be prescribed by your family doctor. Your dietitian will organise this for you.

Are there any foods that I can have freely?

There are a few items that can be added freely to any of the three ketogenic diets. These include carbohydrate free drinks, salt and pepper, herbs, spices and flavourings. Calorie free sweeteners can be used to sweeten foods.

Depending on which diet you choose, your dietitian will provide a list of the foods allowed freely.

Which drinks can I have?

Water is encouraged as a drink. However any carbohydrate free drink such as diet fizzy drinks, soda water, sparkling water and low calorie fruit squash are suitable. Unsweetened tea and coffee can be taken if desired.

Sugar free squash:

It is important to always read the label as some squashes can be labelled as ‘no added sugar’ but can still contain a significant amount of carbohydrate and are not suitable.

Suitable carbohydrate content:

0.6g carbohydrate or less per 100ml of undiluted drink


0.1g carbohydrate per 100ml of diluted drink

Which artificial sweeteners may I use?

Artificial sweeteners can be used in place of sugar to sweeten foods:

  • Saccharin based products eg Sweetex® and Hermasetas® tablets and liquid.
  • Stevia based products eg Truvia® (must be the zero calorie variety)
  • Sucralose based products eg Splenda®
  • Erythritol based products eg Native® icing sugar and powdered sweetener
  • Aspartame sweetener can be used in moderation eg Canderel ®

Sugar free flavoured syrups

  • Try Da Vinci® or Walden farm® sugar free syrups. These can be added to drinks or added to desserts, cream or used in baking.

Avoid using diabetic products as these often contain carbohydrates.

If you are not sure if a sweetener or flavouring is suitable please check with your Dietitian.

Will I need a vitamin and mineral supplement?

Carbohydrate free multi vitamin and mineral supplements are advised when a restricted diet, such as a ketogenic diet is prescribed.

Your dietitian will discuss a suitable supplement with you.

What will happen to my medications?

When you start KDT, your usual medications will not be changed. However, the form they are given in may need to be changed to a lower carbohydrate option.

Tablet medications contain the least carbohydrate. Liquid medications containing sugar should be avoided.

Some medications are available as sugar free liquids, however some of these contain other sources of carbohydrate.

The following list of ingredients will help your pharmacist choose the best form of your medication for you.

Ingredients which are sources of carbohydrate:

  • Sugars: dextrose, fructose, glucose, lactose, sucrose, sugar
  • Starches: cornstarch, pregelatinised starch, sodium starch glycolate, sodium starch glycolate
  • Hydrogenated starch hydrolysates (HSH)
  • Maltitol
  • Isomalt
  • Sorbitol
  • Xylitol
  • Mannitol
  • Alcohol
  • Glycerine
  • Ascorbic acid

Ingredients which are not sources of carbohydrate:

  • Cellulose
  • Carboxymethylcellulose
  • Hydroxyethylcellulose
  • Microcrystalline cellulose
  • Polyethylene glycol
  • Magnesium stearate
  • Aspartame
  • Saccharine
  • Acesulfame potassium (K)
  • Erythritol

What will I do when I am unwell?

When unwell, the amount of ketones produced will fall, eg if you have a cold or a fever.

You should continue to eat your ketogenic meals if possible, or have a suitable ketogenic ‘milkshake’ to replace meals.

If this is not possible, ensure you take adequate fluids. Use carbohydrate free drinks such as water or carbohydrate free fruit squash.

If you have been vomiting or have diarrhoea consider using an oral rehydration solution, eg Dioralyte® (this is available over the counter at a pharmacy). It is usually recommended that Dioralyte® is only used for 24 to 48hrs. Contact your GP and dietitian if illness persists.

Restart the ketogenic diet slowly, with half portions to begin with, building up to full meals over a couple of days.

Can I use pain relief whilst on KDT?

Paracetamol and ibruprofen medications can be used as directed by the manufacturer. Choose tablet forms which will contain the least amounts of additional carbohydrate.

If choosing liquid paediatric pain relief always choose sugar free varieties to minimise the carbohydrate content. Calpol six plus ‘fast melts’ are also low in carbohydrate. They can be used if age appropriate.

What if I need antibiotics?

If you have an infection or are unwell, your doctor will advise you on the medication that needs to be prescribed. Always ensure it is given in the form lowest in carbohydrate.

Ask your doctor or pharmacist to check new medication for you.

How will I measure my ketone level?

When on KDT you will be required to measure you ketone levels daily. This will allow the diet to be monitored and modified to ensure it is most effective.

Ketones are measured in the morning before the first feed of the day (breakfast), and before the last feed of the day (supper). The ketones are often lower in the morning after the overnight fast.

The aim is to have moderate to high ketosis. If measured in the urine the ideal range is 4-16 mmol/L ( or ++ to ++++). If measured in blood the ideal range is 2 to 5 mmol/L. Ketones over 5 mmol/L need to be monitored closely. Ketones can be measured either in the urine or in blood. Your dietitian will advise you on how to monitor ketones.

Where can I get more information?

We recommend the following websites, which provide a wide range of reliable information on the ketogenic diet.

Our contact information

Dietitians 01223 216 655: queries about the diet, ketones, low blood sugars or high ketones, change of feed regime, or home delivery company.

Neurology nurses 01223 216 662: queries about increases in seizures, change in medications and other concerns.

In an emergency, contact the paediatric neurology on-call registrar.

During working hours, call the Child Development Centre01223 586618.

Out of hours or at the weekend, call Addenbrooke’s Hospital on 01223 245151 and ask for the on-call paediatric neurology registrar.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151