According to the American Cancer Society, an estimated 2 million Americans will be diagnosed with cancer in 2025. That’s roughly 5,600 cases daily.
Keto Diet to Prevent Cancer: What the Science Says
With rates this high, many patients are seeking alternative treatments, including the ketogenic (keto) diet. But does the science back the claims?
Let’s explore what the keto diet consists of and examine what the research says about using it to heal from cancer.
What is the keto diet?
The ketogenic diet is a high-fat, very-low-carb eating plan that generally allows:
- 70-80% of daily calories from fat
- 10-20% protein
- 5-10% carbohydrates
Most people on this diet consume only about 50 grams of carbs per day, compared to the customary 200 to 275 generally recommended. This drastic carb reduction pushes the body into ketosis, a metabolic state in which the body burns fat for fuel instead of glucose.
Think of ketosis as the body’s backup power system. When glucose–its first readily-available source of energy–runs low, the body utilizes stored fat for energy instead. This shift naturally induces weight loss, a benefit confirmed by many studies.
However, keto wasn’t originally designed for weight management. Doctors actually developed it to treat epilepsy in children in the 1920s, and researchers have since explored its potential to assist with treatments for a number of other diseases, including:
- Diabetes
- Neurological conditions
- Polycystic ovarian syndrome (PCOS)
- Weight loss
- Cancer
Does the keto diet prevent cancer from spreading?
Research suggests that keto can slow tumor growth by depriving cancer cells of glucose, which is their primary fuel source.
This idea dates back to the 1920s, when German scientist Otto Warburg found that cancer cells rely on glucose for energy, particularly through a process using anaerobic metabolism (without oxygen).
At the time, Warburg believed dysfunctional mitochondria and abnormal metabolism caused cancer. However, current research indicates that gene mutations are the driving force behind the disease, and cancer cells’ glucose dependence simply happens as a result of their rapid growth.
On a keto diet, the body can’t convert fat into glucose, so it produces ketones–an alternative fuel that cancer cells often struggle to use. Animal studies confirm this effect, as do small-scale human studies.
One large review even documented a 22% tumor reduction in girls with brain cancer due to the keto diet.
The ketogenic diet for cancer treatment’s side effects
Aside from its potential as a complementary therapy, research suggests keto can also help manage side effects of conventional cancer treatment. One study found these ultra-low-carb diets may:
- Reduce hyperglycemia (high blood sugar) in patients taking cancer drugs known to cause this problem
- Amplify the effectiveness of anticancer drugs
- Improve patients’ quality of life
Risks for cancer patients
Despite these promising study results, we cannot yet definitively say keto is an effective standalone cancer treatment. According to the research thus far, it’s better used alongside traditional treatments–and there are some considerations and risks.
The first consideration is that the diet can be challenging to follow, and may itself cause symptoms that make treatment more difficult, including:
- Unintentional weight loss
- Nausea
- Fatigue
Research also suggests keto may carry these risks for cancer patients:
Cancer growth
Interestingly, some studies on breast cancer patients suggest ketones may actually accelerate tumor growth instead of slowing it.
Researchers call this the beta-OHB (beta-hydroxybutyrate) paradox, a condition in which a ketone known for its anti-inflammatory and potentially anti-cancer effects fuels certain tumors instead of starving them.
Furthermore, a recent study on breast cancer in mice found that those on a keto diet developed more lung metastases (secondary malignant growths) than those on a standard diet. Researchers traced this to BACH1.
BACH1 is a protein that cancer cells activate when glucose is low, making it easier for them to spread. Scientists are now exploring ways to suppress this protein while maintaining keto’s potential benefits for cancer treatment.
Cachexia
Keto could also trigger cachexia in pancreatic & colorectal cancer patients. Cachexia is a severe “wasting syndrome” that leads to:
- Weight loss
- Fatigue
- Immune suppression
- Difficulty tolerating conventional treatments
However, corticosteroid drugs may help prevent this condition by replacing a missing hormone that regulates metabolism.
The verdict on cancer and low-carb diets
While research is still in its early stages, the keto diet certainly shows promise in cancer therapy.
Some experts, including Dr. Jocelyn Tan-Shalaby, a Medical Oncologist at the University of Pittsburgh School of Medicine, believe that keto is generally safe and unlikely to cause long-term harm.
However, many–again including Dr. Tan-Shalaby–agree that this diet alone is not a primary cancer treatment. Rather, it’s a feasible complementary therapy to be used alongside conventional treatments like chemotherapy and surgery.
If you’ve been diagnosed with cancer, it’s natural to feel scared and overwhelmed while searching for every possible option. But before trying keto, talk to your doctor to see if it fits into your treatment plan.
Together, you can explore the best combination of proven therapies to support you on your healing journey.
References:
Cancer statistics, 2025 – Siegel – 2025 – CA: A Cancer Journal for Clinicians – Wiley Online Library
History of the ketogenic diet – PubMed
Ketogenic Diet – StatPearls – NCBI Bookshelf
The emerging role of ketogenic diets in cancer treatment – PubMed
Ketogenic Diets and Cancer: Emerging Evidence – PMC
In Silico Evidence for Gluconeogenesis from Fatty Acids in Humans – PMC
Uncovering BTB and CNC Homology1 (BACH1) as a Novel Cancer Therapeutic Target
The Pros and Cons of Low Carbohydrate and Ketogenic Diets in the Prevention and Treatment of Cancer
is a freelance health writer, web copywriter, and passionate wellness enthusiast. She’s on a mission to help wellness-focused companies everywhere educate, engage, and inspire their audiences to make the world a healthier, happier place. Learn more about her at copybycarrie.com or on 
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