A therapeutic diet is one that is used in the treatment of a medical condition and can be prescribed by a physician and implemented by them, or prescribed by a physician and implemented by a dietitian. When implemented by a dietitian, a therapeutic diet is referred to as Medical Nutrition Therapy (MNT) .
A ketogenic diet is a very high fat diet that induces and sustains a state of ketosis, which is a natural metabolic state where the body burns fat as its primary fuel, rather than carbohydrate. Ketosis is where the ketone body betahydroxybutyrate (BHB) reaches levels between 0.5 – 3.0 mmol/L known as nutritional ketosis  — right up to levels of 4.0 mmol/L for specific therapeutic ketogenic diets used in the treatment of epilepsy and seizure disorder, or levels of up to 3.0 mmol/L when used as adjunct treatment along with chemo and radiation, in glioblastoma [4,5,6]*.
*Just because a therapeutic diet may be useful in glioblastoma, one should not assume it is an appropriate adjunct treatment for all types of cancer, or in all types of glioblastoma. Some types of cancer feed on glucose, whereas other feed on ketone bodies.
Types of Therapeutic Ketogenic Diets
Ketogenic diets are a subtype of a low carbohydrate diets.
Low carbohydrate diets are ones where carbohydrate intake is limited to <130 g per day or < 26% of total energy intake but that level of carbohydrate intake is much too high for therapeutic purposes in the treatment of epilepsy or seizure disorder, or as adjunct treatment of glioblastoma but are used in the treatment of type 2 diabetes.
Moderate carbohydrate diets are where carbohydrate intake is limited to 130–225 g per day or 26–45% of total energy intake  and while this level of carbohydrate intake can be helpful in the treatment of type 2 diabetes and obesity, a much lower level of carbohydrate intake is required for the treatment of epilepsy, seizure disorder or as adjunct treatment in glioblastoma.
A very low carbohydrate diet is also called a “ketogenic diet” and is one where carbohydrate intake is limited to 20-50 g per day or 10% of total energy intake. It can be used safely and effectively in the treatment of type 2 diabetes and obesity , and is also used the treatment of epilepsy, seizure disorder , and as adjunct treatment in glioblastoma [4,5,6]. The carbohydrate content of the diet is kept very low, so as a result protein and/or fat need to be increased significantly.
In therapeutic ketogenic diets used for obesity management and for seeking remission from the symptoms of type 2 diabetes, protein intake can range from 15% of calories as protein right up to 35-40% of calories. Since it is a very high fat, low carbohydrate diet it induces a state of nutritional ketosis where the primary ketone of interest, betahydroxybutyrate (BHB) can range from 0.5 -3.0 mmol/L.
For the treatment of epilepsy and seizure disorder or as adjunct treatment in glioblastoma, a much lower level of protein is required so that for therapeutic purposes, levels of betahydroxybutyrate (BHB) can reach between 3.0 and 4.0 mmol/L (depending on the specific condition and length of time the person has been following a therapeutic ketogenic diet).
Therapeutic Ketogenic Diets for Epilepsy, Seizure Disorder and Adjunct Treatment in Glioblastoma
A therapeutic ketogenic diet has been used prior to the 1920s by Dr. Russell Wilder for the treatment of diabetes and later for the treatment of epilepsy, in fact it was Wilder himself who is credited with coining the term “ketogenic diet”. The precise percentage of carbohydrate, fat and protein in what is now called the “classic” Ketogenic Diet (KD) was worked out by Dr. M.G. Peterman in 1925 , and are the same ratios used today.
Therapeutic ketogenic diets used in epilepsy and seizure disorder and as adjunct treatment in glioblastoma are very high fat, low protein and low carbohydrate diets — ranging from 4 : 1 ratio (4 parts fat for every 1 part protein plus carbohydrate) to a 3 : 1 ratio (3 parts fat for every 1 part protein plus carbohydrate) — and for maintenance may be as low as a 2 : 1 ratio (2 parts of fat for every 1 part protein plus carbohydrate).
The Diet Prescription
Based on the diet prescription written by the doctor, the amount of energy (calories) that the person needs will be calculated based on the person’s weight and height, activity level, and nutritional requirements and whether there is a goal to avoid weight loss, such in glioblastoma treatment.
Given the very high fat, low carbohydrate content of a 4 : 1 and 3 : 1 ketogenic diet, and the very small amount of protein, Meal Plan design is time-consuming and challenging. It’s not that easy to come up with palatable food combinations that meet the precise macros (amount of protein, fat and carbohydrate) of the diet. Each meal has to have the exact amount — as it is a diet prescription. In a therapeutic diet, the amount and types of food are an integral part of treatment. Just as medication has a “dosage”, the specific and exact amount of food on the diet prescription is like the “food dosage”.
Vitamin, mineral, and trace element supplementation (such as potassium citrate) are also necessary to avoid nutritional deficiencies and recommendations are provided along with the Meal Plan.
In working with adults who are trialing a 4 : 1 or 3 : 1 ketogenic diet for seizure disorder, or during chemo and radiation for glioblastoma, I do the diet calculations, and then design a simple breakfast-lunch-and-dinner Meal Plan for them to use during the initial 6 weeks. Sometimes people with will want an extra dinner meal to alternate with.
If things go well and the diet is improving their symptoms, those with seizure disorder may decide to stay on the therapeutic diet over an extended period of time, and in such a case, I may be asked to design a few lunch and dinner options — with most people content to eat the same breakfast.
Those with glioblastoma will usually ask me to design a 2 : 1 Modified Atkins Diet for them to follow between rounds of chemo and radiation, which I will do for them. This allows for more protein in their diet (while still keeping the carbohydrate content low) and provides a pleasant ‘break’ for those who have been finding the restrictive meals of a 4 : 1 or 3 : 1 ketogenic diet difficult. The other advantage is that since it is unknown whether the type of glioblastoma involved may feed on ketones, alternating between a high ketone and low ketone diet in this manner minimizes providing high ketone levels when not taking the chemo- or radiation treatment.
What is challenging for those first starting out in eating a therapeutic ketogenic diet for epilepsy or as an adjunct treatment in glioblastoma, is that the amount of food on the final Meal Plan must be precisely and accurately weighed — as even the smallest amount of vegetable (which has some protein and some carbohydrate in it) can affect the macros, and thus reduce the therapeutic benefit of the diet. Everything needs to be weighed to the gram.
In addition, at the beginning there is the need for daily monitoring of blood ketone levels to determine when the person has achieved the desired therapeutic range, which for epilepsy and seizure disorder is often where betahydroxybutyrate (BHB) is between 3.0 and 4.0 mmol/L. Once they are able to keep it there by maintaining the diet, testing less frequently is possible.
Classic Ketogenic Diet (KD) – 4 : 1
In the classic Ketogenic Diet (KD), the total amount of calories are matched to the number of calories the person needs. Protein is usually determined as being 1 g of protein per kg body weight, 10-15 g of carbohydrate per day total, and the remainder of calories provided as fat. For very young children, the diet may be prescribed based on body weight (e.g. 75-100 calories for each kg (2.2 pounds) of body weight.
Since the 1920s, several other therapeutic ketogenic for the treatment of epilepsy and seizure disorder have been developed, including the Modified Ketogenic Diet (MKD) and the Modified Atkins Diet (MAD). They are all very low carbohydrate diets high fat diets which is by definition what makes them ketogenic, differ in the amount of protein they contain.
As well as their use in epilepsy and seizure disorder, any of the above therapeutic ketogenic diets may be prescribed for patients as adjunct treatment in glioblastoma, or as adjunct treatment in Alzheimer’s disease.
The classic Ketogenic Diet (KD) has a 4:1 ratio i.e. 4 parts of fat for every 1 part protein and carbs. That is, for every 5 grams of food there are 4 grams of fat and 1 gram of protein and/or carbohydrate.
In the classic Ketogenic Diet, 80% (i.e. 4÷5=80%) of calories come from fat and 20% (i.e. 1÷5=20%) from a combination of protein and carbohydrate.
Protein may be set at 15% of calories with a maximum of 5% of calories coming from carbohydrate, or protein may be set lower at 10%, and carbohydrate as high as 10%.
Modified Ketogenic Diet (MKD) – 3 : 1 ratio
The Modified Ketogenic Diet (MKD) has a 3:1 ratio i.e. 3 parts fat for every 1-part protein and carbohydrate. In a Modified Ketogenic Diet, 75% of calories come from fat and 25% from a combination of protein and carbohydrate. Protein may be set at 15% of calories with a maximum of 10% of calories coming from carbohydrate.
Modified Atkins Diet (MAD) – 2 : 1 ratio
The Modified Atkins Diet (MAD) has a 2 : 1 ratio, with 2 parts fat for every 1-part protein and carbohydrate. In a Modified Atkins Diet, carbohydrates are restricted to <15 g / day for children, <20 g / day for adults. In a Modified Atkins Diet for adults, 60% of calories come from fat, 30% of calories come from protein, and 10% of calories come from carbohydrate.
“Chasing Ketones” – betahydroxybutyrate, the therapeutic goal
The therapeutic goal of a 4 : 1 or 3 : 1 therapeutic ketogenic diet is to get the person’s blood ketone level (as measured with an accurate meter!) to measure 3.0 mmol/L betahydroxybutyrate (BHB) as soon as possible — and to have them sustain it at that level (or in some cases, up to 4.0 mmol/L). Since it is the ketones that provide the therapeutic benefit, not adding anything to the diet that isn’t part of the diet prescription is important.
I usually recommend for a person starting out on a therapeutic ketogenic diet get a Abbott Precision Freestyle Neo meter from their pharmacy, as it measures both blood glucose and ketones, is very accurate and reliable (unlike some purchased online and used by people following the popularize “keto diet” or weight loss) and is provided at no cost when purchasing 100 glucose strips (~$1 each). I then recommend they purchase 30 ketone strips for the same monitor ($3 each) — so the strips will last a month with checking blood glucose 3x / day and checking ketones 1 x / day.
Blood glucose should not go below 4.0 mmol/ L when measured using the glucose strip in the meter, and blood ketone levels should ideally measure 3.0 mmol/L (and as high as 4.0 mmol/Lin epilepsy and seizure disorder – but not over). If ketones exceed 4.0 mmol/L, the person should contact their doctor — and if they go much higher, should seek medical help immediately.
People diagnosed with glioblastoma ideally begin a 4 : 1 (or 3 : 1) therapeutic ketogenic diet upon discharge from hospital so that they begin chemo and radiation treatment already at a ketone level of 3.0 mmol/L betahydroxybutyrate. For seizure disorder, the neurologists that refer their patients to me are seeking levels as close to 4.0 mmol/L as possible — because that is where the most benefit is seen. Once seizures have ceased, people can begin to try gradually eating a 3 : 1, then a 2 : 1 diet — so long as their seizures remain in remission. There is a lot of trial and error involved, but for those seeking to extend their life (as in glioblastoma) or improve their quality of life (as in epilepsy or seizure disorder), it may be worth it.
While people following the popularized “keto diet” for weight loss or remission of type 2 diabetes are often teased about “chasing ketones” — when their goal is fat loss or improved blood sugar (and not producing high levels of ketones!), for those following a therapeutic ketogenic diet for the treatment of epilepsy or seizure disorder, “chasing ketones” between 3.0 mmol/L and 4.0 mmol/L may be desirable.
NOTE: (April 13, 2021): While some research papers indicate that advanced gliomas do not use ketones as a fuel source, a research paper from September 2020 was brought to my attention which calls this into question. According to this paper, there are different types of glioblastoma cells and some oxidize fatty acids and use ketones for energy. Since it appears that when glucose levels are decreased, some types of glioblastoma cells may adapt by partially shifting their metabolism to use oxidized fatty acids and ketones, seeking lower level of ketone production may be advantageous.
[Sperry J, Condro MC, Guo L, et al, Glioblastoma Utilizes Fatty Acids and Ketone Bodies for Growth Allowing Progression during Ketogenic Diet Therapy, iScience Volume 23, Issue 9, 25 September 2020, 101453].
Many thanks to Cliff Harvey, PhD. for rounding out this understanding.
If you would like more information about how I support adults with epilepsy or seizure disorder, or those diagnosed with glioblastoma who are seeking to use a therapeutic ketogenic diet as adjunct treatment (along with chemo and radiation), please send me a note through the Contact Me form.
If you are newly diagnosed with glioblastoma, I will fit you in even when I have no openings for the next several weeks. Your clinical needs are a priority.
To your good health!
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- U.S. Department of Health and Human Services: Final MNT regulations. CMS-1169-FC. Federal Register, 1 November 2001. 42 CFR Parts 405, 410, 411, 414, and 415
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