Scientists looked at 23 studies about whether a ketogenic diet—a special eating plan that’s very low in carbs and high in fat—might help cancer patients. The ketogenic diet changes how your body gets energy, and researchers wondered if this could slow down cancer growth. Most studies focused on brain cancer, with some looking at breast, ovarian, and pancreatic cancers. The review found promising signs that this diet might help improve cancer treatment outcomes, but scientists say more research is needed before doctors can recommend it as a standard cancer treatment.

The Quick Take

  • What they studied: Whether eating a ketogenic diet (very low carbs, high fat) could help cancer patients by changing how cancer cells get energy
  • Who participated: The review looked at 23 published studies from 1990 to 2023. Most studies involved brain cancer patients, with some including breast, ovarian, and pancreatic cancer patients. The exact number of total patients across all studies wasn’t specified in the summary.
  • Key finding: Nearly all studies reviewed showed that the ketogenic diet may have helpful effects on cancer treatment outcomes, suggesting it could be a useful addition to standard cancer care.
  • What it means for you: While results are encouraging, this is still early-stage research. Cancer patients should NOT start a ketogenic diet without talking to their doctor first, as it may interact with treatments or not be safe for everyone.

The Research Details

This was a scoping review, which means researchers searched through scientific databases to find and summarize all available studies on ketogenic diets and cancer from 1990 to 2023. They followed strict guidelines called PRISMA to make sure they found studies fairly and didn’t miss important ones. The researchers looked at different types of studies, including clinical trials (where patients are randomly assigned to different treatments) and case reports (detailed stories of individual patients). They focused on studies that tested whether the ketogenic diet actually helped cancer patients, not just laboratory experiments with cancer cells in dishes.

This approach is important because it gives us a big-picture view of what scientists have already discovered about ketogenic diets and cancer. By looking at many studies together, researchers can spot patterns and see which types of cancer have the most evidence. This helps doctors and patients understand what we know and what we still need to learn before recommending this diet as a cancer treatment.

This review included both strong studies (clinical trials with many patients) and weaker studies (case reports about single patients). The fact that most studies showed positive results is encouraging, but the review didn’t deeply analyze how well each study was done. More high-quality clinical trials are needed to be sure the diet really works. The review covered a long time period (33 years), which is good for seeing how research has developed.

What the Results Show

Out of 23 studies reviewed, nearly all found that the ketogenic diet may help improve cancer treatment outcomes. The strongest evidence came from brain cancer research, with 12 studies focusing on this area, particularly a type called glioblastoma multiforme. The review found 10 clinical trials (the most reliable type of study) across different cancer types: 4 for brain cancer, 2 for breast cancer, and 4 for ovarian cancer. These clinical trials generally showed positive results, suggesting the diet might help patients alongside standard treatments like chemotherapy or radiation.

The ketogenic diet appears to work by changing how cancer cells get energy. Normal cells can switch between using sugar and fat for fuel, but cancer cells often depend heavily on sugar. By eating very few carbohydrates, the ketogenic diet may starve cancer cells while keeping healthy cells functioning. This is why researchers think it could be a helpful addition to cancer treatment.

Breast and ovarian cancers also showed promising results in the studies reviewed, with 4 studies on breast cancer and 4 on ovarian cancer. Pancreatic cancer had fewer studies (3), but those also suggested potential benefits. The review noted that across different cancer types, the pattern was consistent: patients who followed a ketogenic diet alongside their regular cancer treatment appeared to have better outcomes.

The review found that case reports (detailed stories of individual patients) also supported the potential benefits of the ketogenic diet for brain and breast cancer patients. While case reports are less reliable than clinical trials because they only describe one or a few patients, they provided additional evidence that the diet might be worth studying further. The long time period of the review (1990-2023) showed that interest in this approach has grown significantly in recent years, with more recent studies being conducted.

This review builds on growing scientific interest in how diet affects cancer. Previous research has shown that what we eat can influence cancer risk and treatment success. The ketogenic diet is relatively new as a cancer therapy approach, but it fits with existing knowledge that cancer cells behave differently from normal cells. This review adds to the evidence that dietary approaches might be useful alongside traditional cancer treatments, though it’s still considered experimental.

The review has several important limitations. First, the studies included varied greatly in quality and size—some were large clinical trials with hundreds of patients, while others were case reports about just one or two people. Second, the review didn’t deeply analyze how well each study was conducted, so we can’t be completely sure all the positive results are reliable. Third, most evidence focused on brain cancer, so we know less about whether the diet works equally well for other cancer types. Finally, the review didn’t look at potential side effects or whether the diet might interfere with cancer treatments. More large, well-designed studies are needed before doctors can confidently recommend this diet to all cancer patients.

The Bottom Line

Based on current evidence, the ketogenic diet shows promise as a possible addition to standard cancer treatment, particularly for brain cancer. However, confidence in this recommendation is moderate because most studies are small and more research is needed. Cancer patients interested in trying a ketogenic diet should discuss it with their oncologist (cancer doctor) first. The diet should never replace standard treatments like chemotherapy, radiation, or surgery, but might be used alongside them. Patients should work with a registered dietitian who understands both cancer treatment and ketogenic diets.

This research is most relevant for people with brain cancer (especially glioblastoma), breast cancer, ovarian cancer, and pancreatic cancer. However, anyone with cancer should talk to their doctor before making major diet changes. People with certain medical conditions (like diabetes or heart disease), those taking specific medications, or pregnant women should be especially cautious and get medical approval. This research is NOT a substitute for standard cancer treatment and should only be considered as a potential addition to proven therapies.

If a cancer patient and their doctor decide to try a ketogenic diet, benefits might take several weeks to months to appear. Some studies showed improvements in tumor markers (blood tests that measure cancer activity) within weeks, while others took longer. It’s important to have realistic expectations—the diet is not a cure and works best as part of a complete treatment plan. Regular monitoring with blood tests and imaging scans will help determine if the diet is helping.

Want to Apply This Research?

  • Track daily carbohydrate intake (aim for under 50 grams per day for ketogenic diet) and log any side effects or changes in energy levels. Record weekly weight and how you feel during cancer treatment.
  • Work with your medical team to gradually transition to a ketogenic diet if approved. Start by reducing refined carbohydrates and sugary foods, then increase healthy fats from sources like nuts, avocados, and olive oil. Use the app to plan meals and track macronutrients (carbs, proteins, fats).
  • Monthly check-ins with your oncologist and dietitian to review diet adherence, side effects, and any changes in cancer markers. Use the app to share food logs and symptom reports with your healthcare team to ensure the diet isn’t interfering with treatment.

This review summarizes research on ketogenic diets and cancer, but it is NOT medical advice. Cancer is a serious disease that requires professional medical care. Do NOT start a ketogenic diet or change your cancer treatment without first consulting with your oncologist and a registered dietitian. The ketogenic diet should never replace standard cancer treatments like chemotherapy, radiation, or surgery. Some people cannot safely follow a ketogenic diet due to other health conditions or medications. Always work with your healthcare team before making any dietary changes during cancer treatment. If you have cancer, speak with your doctor about whether a ketogenic diet might be appropriate for your specific situation.