Waiting in line at the grocery store, you’ve seen the headlines touting the health benefits of the ketogenic diet. (Admit it, you look at those magazines too!)
But did you know the modern keto diet has been around for almost 100 years?
In 1921, Dr. Russell Wilder at the Mayo Clinic first used the diet to treat epilepsy. He coined the term “ketogenic diet,” and for almost a decade, the diet was widely used until anticonvulsants (antiepileptic or antiseizure drugs) became commonplace.
What makes the keto diet so enticing to many is that when the body reaches “ketosis,” it burns fat instead of carbs, glucose – the primary energy source for the body.
You’re probably thinking, “Whoa! A fat-burning diet is just what I need!” And since cancer cells need sugar for energy, shouldn’t every cancer patient embrace the ketogenic diet?
Maybe – and no. Much like a relationship status on Facebook, it’s complicated.
As we’ll discuss, there are pluses and minuses to the keto diet. Truth be told, every diet has its talking points (and things no one wants to talk about.) You should have a frank conversation with a doctor or nutritionist before starting any diet.
Also, not all low-carb diets are the same. There is research that shows different mortality rates between animal-based, low-carb diets and plant-based, low-carb diets.
You also will read several words that start with keto – ketogenic, ketones, ketosis, and ketoacidosis. It will be easy to skim past k-e-t-o – but beware, each of these words is different especially ketoacidosis.
Now, there is a pause for caution. The high level of saturated fat combined with strict limits on fruits, vegetables, and grains is not optimum for long-term heart health.
So, are you ready to learn more about the hubbub regarding the keto craze?
What to know about the keto diet
Dr. Rusell Wilder used a ketogenic diet in a series of patients with epilepsy. His premise was that the keto diet could be as effective as fasting and maintained for a longer time.
Between 1941 and 1980, textbooks on epilepsy in children included the ketogenic diet, which was used extensively in the 1920s and '30s. In 1972, Dr. Samuel Livingston reported on more than 1,000 children that he had followed during previous decades. His research showed 52% of the patients had complete control of seizures, while 27% had improved control. 
The Epilepsy Foundation details the keto diet for children.
“The ketogenic diet is a high fat, moderate protein, very low carbohydrate diet that promotes rapid weight loss,” notes Kristen Mancinelli, MS, RDN. “It consists of about 75-80% of calories from fat, 10-15% from protein, and 5-10% from carbs. This approach to weight loss has come in and out of favor over the years in line with ever-changing beliefs about the link between dietary fat intake, weight gain, and heart disease.
“We are now in a period where nutrition experts and policymakers are moving away from recommendations to lower fat intake and instead are advising individuals to reduce sugar consumption as a means to lose weight and promote optimal health.”
Your body’s primary fuel for energy is glucose. Glucose production comes from the carbohydrates we eat (bread, rice, pasta, sugar, certain fruits, and vegetables).
When you drastically reduce your consumption of glucose, the body starts looking for other sources of energy. It starts burning fat for fuel instead of glucose. Once your body starts running off of fat, it begins producing ketones and places your body in a state of ketosis.
What is ketosis
Ketosis is a metabolic state in which your liver produces ketones and burns fat for energy instead of glucose. It typically takes between 7-30 days after starting the diet for your body to be fully in ketosis.
Physicians can do a blood, urine, or breath test to find out if you are producing ketones. Blood work is the most reliable and accurate way to measure ketones. It measures the amount of beta-hydroxybutyrate in your blood, which for nutritional ketosis, the ketone levels should be between 0.5-3 millimoles per liter. 
Home blood, urine, and breath kits can be expensive but are available online.
Symptoms of ketosis
- Increased Ketones: can be measured at home or by your physician.
- Bad breath: with ketosis, more acetone leaves the body, which causes bad breath.
- Weight loss
- Thirst (water loss): ketosis can lead to dehydration, which can cause muscle cramps and spasms. It is essential to increase your consumption of water and keep hydrated.
- Change in sleeping habits (insomnia): this typically improves in a few weeks after adapting to the diet.
- Headaches: remain a common symptom when starting the diet, as your body is adapting to consuming fewer carbohydrates along with possible dehydration and electrolyte imbalances. It is essential to consult a doctor if your headache doesn't go away.
- Upset stomach and digestive issues: Some people experience constipation or diarrhea when starting the diet, but these symptoms should improve once adapted to the menu.
- Fatigue and weakness: this is, again, typically short-term. Studies have shown an increase in focus and energy after adaptation. 
Misconceptions of the ketogenic diet
One of the most common misconceptions of the keto diet is confusing the term ketosis for ketoacidosis.
Ketosis occurs when the body starts using fat as the primary source of energy instead of glucose, and the liver begins producing ketone bodies. This is a normal metabolic state.
However, ketoacidosis can be very dangerous. It happens when the blood starts breaking down fat too fast, and the liver produces an extreme number of ketones.
This can become life-threatening because the blood will become acidic. It most commonly occurs in patients who have diabetes, severe alcohol abuse, and also has occurred in patients during lactation. 
Symptoms of Ketoacidosis:
- Nausea and vomiting
- Stomach pain
- Muscle stiffness or aches
- Decreased alertness
- Rapid breathing
- Dry skin and mouth
- Frequent urination
- Fruity-smelling breath
- A thirst that lasts for a day or longer
Another common misconception is that you have to eat meat on a ketogenic diet. There are ways to keep a vegetarian and a vegan lifestyle and still do the keto diet as long as you get enough plant-based protein.
The ketogenic diet and the Atkins diet are commonly confused as being the same. They are both low-carb diets, but the keto diet focuses more on healthy fats and is more restrictive than the Atkins diet.
The Atkins diet is a modified version of the ketogenic diet. During the Atkins diet, there are four stages during which you gradually increase carbohydrate intake – so much so that you would no longer be in a ketosis state of metabolism.
Regarding low-carb diets (not to be mistaken with the ketogenic diet), studies have shown a long-term, animal-based, low-carb diet can increase the mortality rate. However, a long-term, plant-based, low-carb diet suggested a lower mortality rate. 
“Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis,” a 2018 study led by Dr. Sara Seidelmann with Brigham and Women's Hospital, noted:
“Low carbohydrate dietary patterns favoring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favored plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain bread, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.”
Keto and cancer
Ketogenic diets mimic fasting, and the body responds to the lack of glucose by producing ketones as a source of energy.
Anecdotal data from case reports and small clinical trials show some promise regarding ketolytic and glycolytic enzymes in treating brain cancer. 
Bottom line: How the ketogenic diet affects cancer needs more research, including more extensive clinical trials.
Two clinical trials – ERGO: A pilot study of ketogenic diet in recurrent glioblastoma and Modified Atkins diet in advanced malignancies – final results of a safety and feasibility trial within the Veterans Affairs Pittsburgh Healthcare System – have posted results. [7, 8]
The ERGO study followed 20 patients with recurrent glioblastoma. The researchers suggested a keto diet can be safely applied to these patients. However, they noted additional research is necessary to clarify a possible role of the ketogenic diet for glioblastoma therapy.
The modified Atkins diet study recruited 17 advanced cancer patients who were not on chemotherapy. Eleven of the patients met the criteria for the study. The results showed steroid intake affected optimal ketone and glucose levels. Still, survival improved in some melanoma and lung cancer patients. On the modified Atkins diet, patients who lost at least 10% of their body weight responded the best. Again, further studies are recommended.
Pluses and minuses of the keto diet
- Potential to improve insulin sensitivity and reduce inflammation for some cancer types 
- Creates an unfavorable metabolic environment for cancer cells
- Preclinical and clinical studies show benefits for the use of a keto diet in combination with standard therapies
- Enhances antitumor effects in patients doing chemo and radiation
- Not enough human trials have been done 
- The diet is notoriously hard to stick to long term
- Many alternative therapies are not compatible with the keto diet
- It is not recommended as a standalone diet (for cancer)
- Can be easily confused with a low-carb diet if done wrong
- Some studies have shown it to accelerate specific brain cancer and certain leukemias
Doctors recommend keto diets in certain circumstances: help control Type 2 diabetes and reduce childhood epileptic seizures. There is limited evidence that a ketogenic diet may help keep extra pounds off, but other studies rebuff that idea. 
The ketogenic diet is not for patients with pancreatitis, liver failure, fat metabolism disorders, primary carnitine deficiency, carnitine palmitoyltransferase deficiency, carnitine translocase deficiency, porphyrias, or pyruvate kinase deficiency.
Remember: “Yo-yo” diets, the ones that lead to weight fluctuation, are associated with increased mortality.  Discuss your nutritional needs with a doctor to ensure a balanced diet with fish, fruits, lean meats, nuts, olive oil, seeds, vegetables, water, and whole grains.
A ketogenic diet is not just low carb; the key is that it’s a low insulin diet.
Implementing KD and the Importance of Calculating Macronutrients
Figuring out and tracking daily macronutrients is extremely important when starting a keto diet. Macronutrients – more commonly called macros – consists of the carbohydrates, fats, and proteins you consume daily. This will directly impact your ability to lose, maintain, or gain weight.
It also will affect whether or not you stay in ketosis, which is the point of a ketogenic diet.
After you find out what your daily macronutrient needs are, you will need to start tracking your food with a macro tracker. Many great apps and websites can simplify this process. Below are a few apps that are user-friendly and compatible with your iPhone or Android.
Carb Manager – Keto Diet app (Free; iPhone and Android compatible)
The Carb Manager app helps you count and keep track of your macros. Some other features include a keto calculator, food diary, nutritional tracker, water tracker, and exercise tracker.
Keto.app (free with in-app purchase options; iPhone and Android compatible)
The Keto.app can count and track your macros, track custom meals, has a database of keto-friendly recipes, and connects to the Apple health app.
My Macros+ ($2.99; iPhone and Android compatible)
The My Macros app can help track your goals by gram or percent, monitor weight, break down meals, track water consumption, and has a recipe database.
Dr. Linda Isaacs' perspective on the ketogenic diet
There are a wide variety of dietary recommendations available online, in books, or in practitioners’ offices, with different amounts of carbohydrates, fat, and protein, each purporting to be helpful to people in general and cancer patients especially. I frequently see patients who are completely confused about what they should eat. One unfortunate gentleman even told me that he had become afraid to eat, wondering if everything was poisonous, with detrimental effects on his weight.
My colleague of more than 20 years, the late Dr. Nicholas Gonzalez, and I have treated many patients over the years with nutritional protocols based on the work of William Donald Kelley, D.D.S. Dr. Kelley was a brilliant clinician and observer, who deduced that different patients needed different diets. Depending on their condition and their innate physiology, Dr. Kelley might put one patient on lots of fruits and a wide array of vegetables, along with whole-grain products, eggs, dairy, and fish, but no red meat or poultry. Another patient might be told to eat fatty red meat, with lots of butter and root vegetables, but minimal to no fruit, leafy greens, or grains.
The dietary recommendations Dr. Kelley gave to patients were on a spectrum between these two extremes. All diets, though, emphasized the use of unrefined and unprocessed organic foods, and all included some vegetable juice made predominantly from carrots.
For cancer patients, the type of cancer typically correlated to Dr. Kelley’s dietary prescription. Patients with carcinomas (including the most common types of cancer such as lung, breast, colon, prostate) were told to eat a more vegetarian diet, while patients with cancers of the immune system such as leukemias and lymphomas were placed on a higher fat diet.
Different diets: remarkable, documented results
With this system, Dr. Kelley got remarkable results, as detailed in Dr. Gonzalez’s book One Man Alone: An Investigation of Nutrition, Cancer, and William Donald Kelley. Since this was the case, in our work, we continued to give different diets to different people, along with individualized supplement protocols and detoxification routines. And we continued to see remarkable results, as detailed in our published articles and in the books Conquering Cancer, Volume 1 and Volume 2.
Dr. Kelley advised his patients not to eat white flour, white rice, sugar, and other refined products. Such foods, he warned, were empty calories, devoid of the minerals and vitamins needed to process them, stripped of the beneficial fiber that helped maintain a healthy gut. But in the last decade, the phrase “cancer feeds on sugar” has spread wildly online and has been used as a rationale to eliminate not only white sugar and white flour, but also carrots, whole grains, and other foods that had previously been considered healthy.
I believe this is an overreaction. I have patients who have thrived for many years, with cancers that should have killed them long ago, who have been drinking carrot juice and eating fruit and whole grain products the whole time. I have spoken with a patient treated by Dr. Kelley in 1975 for metastatic breast cancer, a condition incurable in orthodox medicine. She is alive and well more than 40 years later while eating a diet rich in carbohydrates. A draconian elimination of carbohydrates was not necessary for any of these patients.
Cancer cells get their supply of nutrients from the blood, and it is not physically possible to get the blood sugar low enough to “starve” cancer. The body fights hard to maintain blood sugar in a narrow range. If a patient eats no carbohydrates whatsoever, the protein in the diet will be turned into glucose; if a patient then eats no protein, the protein in the muscles will be turned into glucose. No matter what a patient does, cancer will still get its glucose.
Advocates of carbohydrate restriction may say that the benefits for cancer come about not by “starving cancer” but rather by preventing the elevation in insulin that is triggered by carbohydrate intake. Insulin spikes can be stimulatory to cell growth; the high sugar load of the Standard American Diet (SAD) causes high levels of insulin, which may lead to insulin resistance and elevated blood sugar (Type 2 Diabetes).
Overweight and obese patients are more likely to have such problems, and these patients should certainly take more care with their carbohydrate intake. But I routinely see new patients who are normal weight, or even underweight, who are terrified of eating a piece of fruit or whole grain bread because it will “feed cancer.” Their relief on being told to eat the fruit is palpable.
Teachings based on clinical observation
One concept I do believe is valuable in the teachings of the ketogenic diet advocates is intermittent fasting, which can be simply managed by not eating between dinner and breakfast the following morning, allowing an 11-12 hour window where no food is taken in. This is more typical of how our ancestors ate and how our bodies were designed to work. The gut uses this window to clean itself out. The Standard American Diet (SAD), which frequently involves an evening sitting in front of a screen munching snack foods, is not healthy.
The ketogenic diet is based on theory, along with studies done in cell cultures or laboratory animals in artificial environments. The cancer patient success stories I have read are unconvincing to me – they are few, short-term, and the patients were frequently combining the treatment with other modalities such as chemotherapy. Since I graduated from medical school, I have seen many treatment methods, orthodox and unorthodox, based on theory, that have not survived the acid test of proper investigation and clinical experience.
To their credit, the high-profile advocates of the ketogenic diet are pursuing such testing. I wish them well, and if they are successful, I will change my recommendations. But in the meantime, I will follow in the footsteps of Dr. Kelley, whose teachings were based on clinical observation, and who had the long-term success stories to back them up. And for you out there who are craving a piece of fruit, I suggest you eat it.
Dr. Linda Isaacs offers nutritional protocols for patients with many different conditions, or for those who wish to maintain their health. Learn more at http://www.drlindai.com/
Summary of science
Ketosis is a state of metabolism that, in normal physiology, responds to low glucose availability (low carbohydrate diets or fasting) and provides additional energy to the brain in the form of ketones. Thus, a ketogenic diet is high in fat, moderate to low in protein, and very low in carbohydrates. This ratio of macronutrients causes the body to burn fat instead of glucose to make adenosine triphosphate (ATP), otherwise known as energy, for the body.
In terms of cancer therapeutics, proponents of this regimen suggest that restriction of glucose leads to less energy production (via ATP) in cancer cells. This “energy sink” state is theorized to inhibit cancer growth and encourage cancer cell death.
Pros: Animal studies using the ketogenic diet as a cancer treatment are promising, showing decreased tumor growth and improved survival rates. Clinically, the ketogenic diet has shown great success in controlling epileptic seizures.
As a complementary therapy – in addition to traditional treatments such as chemotherapy, radiation, etc. – the ketogenic diet has shown promise in some cancers, with reduced tumor size, growth, and improvements in physical condition after 3 months of therapy.
Cons: There are few definitive, well-designed clinical trials using the ketogenic diet as a cancer therapy. Additionally, there have been reports of the ketogenic diet accelerating the growth of certain leukemias and gliomas.
Although there are promising studies on the ketogenic diet, more research needs to be done. The keto diet has many contradictions and cannot be used in conjunction with most alternative protocols.
Anytime you are considering a dietary change, it is essential to speak with a physician, especially if you have cancer or other health conditions.
- Comprehensive management of epilepsy in infancy, childhood and adolescence. https://www.amazon.com/Comprehensive-management-epilepsy-childhood-adolescence/dp/B0006C2W3U
- Nutritional Ketosis and Mitohormesis: Potential Implications for Mitochondrial Function and Human Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5828461/
- Low-carbohydrate weight-loss diets. Effects on cognition and mood. Appetite. https://www.ncbi.nlm.nih.gov/pubmed/18804129
- Severe ketoacidosis in breastfeeding woman with low energy and carbohydrate intake. https://www.ncbi.nlm.nih.gov/pubmed/26371480
- Dietary carbohydrate intake and mortality; a prospective cohort study and meta-analysis. https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30135-X/fulltext
- Ketolytic and glycolytic enzymatic expression profiles in malignant gliomas: implication for ketogenic diet therapy. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707813/
- ERGO: A pilot study of ketogenic diet in recurrent glioblastoma. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4063533/
- Modified Atkins diet in advanced malignancies - final results of a safety and feasibility trial within the Veterans Affairs Pittsburgh Healthcare System. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4983076/
- Ketogenic diet in the treatment of cancer – Where do we stand? https://www.ncbi.nlm.nih.gov/pubmed/31399389
- Ketogenic Diets and Cancer: Emerging Evidence. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6375425/
- Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. https://www.ncbi.nlm.nih.gov/pubmed/27385608
- Obesity Pathogenesis: An Endocrine Society Scientific Statement. https://academic.oup.com/edrv/article/38/4/267/3892397