Explained by Thomas N. Seyfried, PhD, Boston College

A 65-year-old woman with brain cancer had surgery to remove the tumor, but the operation couldn’t remove it all. The woman started following the ketogenic diet—a diet very high in fat, moderate in protein and very low in carbohydrate. She also had chemotherapy and radiation. After six weeks on the diet, a brain scan showed that the tumor had disappeared. A brain scan five months later showed it was still gone. However, the patient stopped the diet—and a scan three months later showed that the tumor had returned.

Yes, a special diet called the ketogenic diet can fight cancer. Here is a video of Dr. Thomas H. Seyfried speaking on manipulating energy metabolism in the body to target cancers.

This diet is being used to manage brain cancer and advanced (metastatic) cancer, which is when the disease has spread beyond the original tumor to other parts of the body (such as breast cancer that spreads to the liver and bones). It may be effective in fighting most, if not all, cancers, but it must be done under the supervision of an experienced oncological nutritionist. Here, what you need to know about this little-known therapy for cancer…


The ketogenic diet is very high in fat—the ratio is four grams of fat to one gram of protein/carbohydrate. It has long been used to control epilepsy and is offered as an epilepsy treatment at hundreds of hospitals and clinics around the world, including The Johns Hopkins Epilepsy Center, Mayo Clinic and Mattel Children’s Hospital at UCLA. It eases epilepsy by stabilizing neurons (brain cells). It does so by reducing glucose (blood sugar), the main fuel used by neurons, and increasing ketones (beta-hydroxybutyric acid and acetoacetic acid), a by-product of fat metabolism used by neurons when glucose levels are low. Reducing glucose and increasing ketones play key roles in fighting cancer as well. The typical American diet is about 50% to 60% carbohydrate (fruits, vegetables, breads, cereals, milk and milk products, and added sugars in sweetened foods and beverages). The body turns carbohydrate into glucose, which is used for energy. Cancer cells gorge on glucose. Eating a ketogenic diet deprives them of this primary fuel, starving the cells, which stop growing or die. Also, ketones are a fuel usable by normal cells but not by cancer cells, so this, too, helps stop cancer growth. In addition, the diet… Puts you into a metabolic state similar to that of fasting—and fasting has repeatedly been shown to arrest cancer. Lowers levels of insulin (the glucose-regulating hormone) and insulin-like growth factor—both of which drive tumor growth.


The first case report about the ketogenic diet for cancer appeared in Journal of the American College of Nutrition in 1995. The ketogenic diet was used by two children with advanced, inoperable brain cancer who had undergone extensive, life-threatening radiation and chemotherapy. They both responded remarkably well to the diet. A case report that I coauthored, published in Nutrition & Metabolism in 2010, told the story (see beginning of this article) of the 65-year-old woman with glioblastoma multiforme—the most common and most aggressive type of brain tumor, with a median survival of only about 12 months after diagnosis. Standard treatment—surgery to remove as much of the tumor as possible, plus radiation and/or chemotherapy—extends average survival time only a few months beyond that of people who aren’t treated. My viewpoint: In animal research, the ketogenic diet is the only therapeutic approach that deprives tumors of their primary fuel…stops tumor cells from invading other areas…stops the process of angiogenesis (blood supply to tumors)…and reduces inflammation, which drives cancer. The diet also could reduce the need for anticonvulsant and anti-inflammatory medications in brain cancer patients. Considering how ineffective the current standard of care is for brain cancer (and for metastatic cancer), the ketogenic diet could be an attractive option for many cancer patients.


The ketogenic diet for cancer is not a diet you should undertake on your own after reading a book or other self-help materials. It requires the assistance of an oncological nutritionist or other health professional who is familiar with the use of the regimen in cancer patients. Ask your oncologist for a referral. Important aspects of the ketogenic diet include…

  • Measuring glucose and ketone levels. For the management of cancer, blood glucose levels should fall between 55 mg/dL and 65 mg/dL, and ketone levels between 3 mmol and 5 mmol. In order to monitor those levels—and adjust your diet accordingly—you need to use methods similar to those used by patients with diabetes. These methods include glucose testing several times a day with a finger stick and glucose strip…daily urine testing for ketones…and (more accurate) home blood testing for ketones, perhaps done weekly.
  • Starting with a water-only fast. If you are in relatively good health (aside from the cancer, of course), it is best to start the ketogenic diet with a water-only fast for 48 to 72 hours, which will quickly put you in ketosis—the production of a therapeutic level of ketones. This fast should be guided by a health professional.If you are fragile or in poor health, you can skip the water fast and initiate ketosis with the ketogenic diet, reducing carbohydrates to less than 12 grams a day. This should produce ketosis within two or three weeks.
  • Macronutrient ratios and recipes. Working with a nutritionist, you will find the fat/protein/carbohydrate ratio that works best for you to lower glucose and increase ketones…and the recipes and meal plan that consistently deliver those ratios. A food diary, a food scale and the use of a “KetoCalculator” are necessary tools to implement the ketogenic diet. Helpful: The oncological nutritionist Miriam Kalamian, EdM, MS, CNS, managed her own son’s brain tumor with the ketogenic diet, and she counsels cancer patients around the world in the implementation of the diet. You can find more information on her Web site, DietaryTherapies.com.


Currently, there are several clinical trials being conducted using the ketogenic diet for cancer.

  • Brain cancer. There are trials at Michigan State University and in Germany and Israel testing the diet’s efficacy as a complementary treatment with radiation for recurrent glioblastoma…and by itself to improve the quality of life and survival time in patients with brain cancer. Michigan State University currently is recruiting patients for its trial. Contact: Ken Schwartz, MD, 517-975-9500, e-mail: ken.schwartz@ht.msu.edu.
  • Pancreatic cancer. A trial at Holden Comprehensive Cancer Center at University of Iowa is recruiting patients with pancreatic cancer for a trial using the ketogenic diet along with radiation and chemotherapy. Contact: Bryan Allen, MD, 319-356-3693, e-mail: bryan-allen@uiowa.edu
  • Lung cancer. The University of Iowa also is recruiting lung cancer patients for a similar trial. The contact information is the same as for the trial on pancreatic cancer.
  • Metastatic cancer. The VA Pittsburgh Healthcare System is recruiting patients with metastatic cancer for a study of the effect of the ketogenic diet on quality of life, tumor growth and survival. Contact: Jocelyn Tan, MD, 412-360-6178, e-mail: jocelyn.tan@va.gov.

You can find out more about these trials at ClinicalTrials.gov. Enter “Ketogenic Diet” into the search engine at the site for a complete listing of cancer trials and trials testing the ketogenic diet for other conditions, including epilepsy, amyotrophic lateral sclerosis (ALS), Lafora disease (a severe neurological disease), Parkinson’s disease and obesity.


Cancer survivors and people with a family history of cancer may wonder if they should go on the ketogenic diet as a preventive measure. It is not necessary for people to follow the diet if they do not have cancer. A six-to-seven-day water-only fast done once or twice a year—under a doctor’s supervision—can be effective in reducing the risk for recurrent cancer in survivors and in those individuals with a family history of cancer. Fasting reduces glucose and elevates ketones.