Thomas Seyfried: The Diet That Starves Cancer

Dr. Thomas N. Seyfried, PhD, Professor of Biology at Boston College, has been singing the praises of an ancestral diet for treating the modern disease of cancer for years… and with good reason. His theory that cancer is a metabolic disease sounds almost too simplistic, and yet makes perfect sense when you understand what drives cancer’s growth.

Standard of Care: The Cut and Burn Method and Its Miserable Success Record

Seyfried is not a fan of conventional medical cancer treatments. As he states in his groundbreaking book, Cancer as a Metabolic Disease: On the Origin, Management, and Prevention of Cancer, the majority of today’s health care practitioners are required to prescribe conventional cancer treatments like chemotherapy and radiation—despite their toxicity and the possibility that they encourage new tumor growth. In fact, if a physician does not include these modalities in a treatment plan, the physician may be at risk of losing his medical license.

“Cancer is the only disease I know where you’re poisoning and irradiating people to make them healthy. It makes absolutely no sense. Why are you subjecting patients to all this toxicity when you don’t have to do it?” asks Seyfried. “You can get the same results by reducing glucose and glutamine, but without the toxicity of chemo and radiation.”

A Better Way: Cutting Off Cancer’s Food Supply

Research has shown that cancer thrives on glucose and glutamine. In fact, cancer cells obtain as much as 95 percent of their energy by breaking down these two fuels through a process called glycolysis and the Krebs cycle. Conversely, one way to starve ravenous cancer cells is to simply deny them their preferred fuel.

The diet that does this quite effectively is the ketogenic diet. It is a diet which severely restricts carbohydrates (particularly refined carbohydrates), while promoting higher levels of healthy fats and adequate protein to bring about a state of ketogenesis. Healthy cells, which can survive on ketone bodies and fatty acids, continue to function normally while tumors may shrink or even disappear.

Science has shown that glioblastoma responds especially well to a ketogenic diet. Seyfried: “No tumor cell can survive in the absence of both glucose and glutamine, especially when ketones are used to support the viability of normal cells.”

The Benefits of Fasting and Calorie Restriction

Seyfried asserts that the fastest way to achieve optimal ketosis is to begin with a 3-5 day water-only fast. And research backs him up. One such study published in Cancer Science states, “Emerging evidence suggests that fasting could play a key role in cancer treatment by fostering conditions that limit cancer cells’ adaptability, survival, and growth. Fasting could increase the effectiveness of cancer treatments and limit adverse events.”

If such a water-only fast is prohibitive for you, consider intermittent fasting. It’s a method in which you restrict your meals to a certain number of hours per day, with as much as 18 hours between dinner and breakfast the next morning. It’s not as difficult as it may sound, especially if you’re not a breakfast person. Just put off your first meal of the day until, say, noon. Then eat your last meal of the day before 6 pm.

Dr. Eric Berg is also a proponent of the ketogenic diet as well as intermittent fasting. You can learn more about this method of healing and how it turns on cancer suppressive genes and turns off genes that express cancer here:



NOTE: You’ll want to check with your health care practitioner to be sure this is right for you. Because everyone’s metabolism is different, results will vary.



Christ A, Günther P, Lauterbach MAR, Duewell P, Biswas D, Pelka K, Scholz CJ, Oosting M, Haendler K, Baßler K, Klee K, Schulte-Schrepping J, Ulas T, Moorlag SJCFM, Kumar V, Park MH, Joosten LAB, Groh LA, Riksen NP, Espevik T, Schlitzer A, Li Y, Fitzgerald ML, Netea MG, Schultze JL, Latz E. Western Diet Triggers NLRP3-Dependent Innate Immune Reprogramming. Cell. 2018 Jan 11;172(1-2):162-175.e14. doi: 10.1016/j.cell.2017.12.013. PMID: 29328911; PMCID: PMC6324559.

Seyfried TN. Cancer as a mitochondrial metabolic disease. Front Cell Dev Biol. 2015 Jul 7;3:43. doi: 10.3389/fcell.2015.00043. PMID: 26217661; PMCID: PMC4493566.

Seyfried TN, Yu G, Maroon JC, D’Agostino DP. Press-pulse: a novel therapeutic strategy for the metabolic management of cancer. Nutr Metab (Lond). 2017 Feb 23;14:19. doi: 10.1186/s12986-017-0178-2. PMID: 28250801; PMCID: PMC5324220.

Seyfried, M.D., Thomas. Cancer as a Metabolic Disease: On the Origin, Management and Prevention of Cancer. 2012. First Edition, John Wiley and Sons Inc., Hoboken, New Jersey

Tiwari S, Sapkota N, Han Z. Effect of fasting on cancer: A narrative review of scientific evidence. Cancer Sci. 2022 Oct;113(10):3291-3302. doi: 10.1111/cas.15492. Epub 2022 Aug 10. PMID: 35848874; PMCID: PMC9530862.

Mukherjee P, Augur ZM, Li M, Hill C, Greenwood B, Domin MA, Kondakci G, Narain NR, Kiebish MA, Bronson RT, Arismendi-Morillo G, Chinopoulos C, Seyfried TN. Therapeutic benefit of combining calorie-restricted ketogenic diet and glutamine targeting in late-stage experimental glioblastoma. Commun Biol. 2019 May 29;2:200. doi: 10.1038/s42003-019-0455-x. PMID: 31149644; PMCID: PMC6541653.

Press Release: “Targeting Cancer: An International Research Team Led by A Boston College Professor Has Uncovered A Drug and Diet Pairing That Could Fight A Deadly Brain Cancer,” Boston College (March 23, 2023).

Related Templeton Wellness Articles:

Keto and Paleo Diets: Are They Right for You?

New Study Says This Keto Molecule Suppresses Tumors



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