Calorie Restriction
Intermittent Fasting & the Fasting Mimicking Diet
Fasting may reduce cancer recurrence and weaken cancer cells to make them more sensitive to chemo.
There is good evidence suggesting fasting for 12-13 hours a day can reduce cancer recurrence by 36%. That’s a pretty big benefit with minimal downside. Not eating for 12 hours isn’t very long.
Other research suggests a two-for-one deal; fasting weakens cancer cells making it easier for chemo to kill them while simultaneously reducing the side effects of chemo. Win-win.
“Cycles of starvation were as effective as chemotherapeutic agents in delaying progression of different tumor models
and increased the effectiveness of chemotherapy in melanoma, glioma, and breast cancer cells.”
(note: pre-clinical study of mice)
A 2023 review titled, “Short-term fasting (STF) and fasting mimicking diets (FMD) combined with chemotherapy: a narrative review,” does a good job describing the mechanisms at work and bringing together several important research studies in this space. Most of the evidence provided is positive such as the citation provided above from a preclinical FMD study.
In addition, research found that fasting made cancer cells more sensitive to chemotherapy. “Marked reductions of IGF-1 (insulin growth factor 1) induced by prolonged fasting in rodents and humans also have the potential to preferentially sensitize cancer cells to chemotherapy.” “Glucose starvation, as seen in prolonged fasting and in ketogenic diets, may sensitize cancer cells to the damaging effects of chemotherapy.”
Ultimately, it finds STF and FMD are “promising dietary interventions” but notes that uncertainty persists regarding safety, feasibility, and effectiveness. It provides details about several clinical trials currently underway to address these uncertainties.
Importantly, while FMD may be a beneficial adjunct therapy, there is wide-spread agreement that it is a potential adjunct therapy and not a replacement for the medical standard of care which is established through rigorous research and testing in humans over long periods of time and is proven to be the best path forward for cancer patients.
Research Highlights
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13-hour daily fast associated with a 36 percent decrease in breast cancer recurrence
”In a post-analysis of the Women's Healthy Eating and Living Study, 24-hour dietary recall data was reviewed on >2400 women with a history of breast cancer but without a history of diabetes. The analysis revealed a longer nightly fast was also associated with significantly lower concentrations of HbA1c (average blood sugar over 3 months) and longer sleep duration. It is theorized that the combination of these benefits could reduce the risk of type 2 diabetes, cardiovascular disease, and other cancers (secondary cancer) in addition to the 36% reduction in breast cancer recurrence associated with the 13 hour daily fast.”A 2021 study titled, “Calorie Restriction for Cancer Prevention and Therapy: Mechanisms, Expectations, and Efficacy” reviews the therapeutic potential of calorie restriction to prevent or retard tumor development. They introduce another anti-cancer approach, Caloric Restriction Mimetics (CRM), that relies on the use of nutraceuticals to provide caloric restriction-mediated benefits without subjecting the patients to a strict diet. “Many CRMs are bioactive food components able to elicit anti-proliferative, pro-apoptotic and anti-metastatic effects without fasting. The family of polyphenol substances are all a good source of potential CRMs, since they have a wide range of biological activities, including anti-oxidant, anti-inflammatory, anti-carcinogenic and epigenetic modulation activities.” News flash. They are talking about phenolic acids and derivatives, such as flavonoids… such as broccoli sprouts. Interesting connection!
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FMD produced complete and long lasting tumor responses in some patients
The FMD has demonstrated additive or synergistic antitumor effects when combined with chemotherapy, targeted therapies, or immunotherapies in several preclinical in vivo models, including murine (mouse) models of breast, lung, and colorectal cancer. There are several clincial trials going on now using the FMD and standard chemotherapy. In this Phase 1 / 2 trial of 101 patients with different tumor types, five patients were singled out as exceptional responders. In each case, they had remarkable complete and long lasting tumor responses.Hot off the press – August 21, 2023. “Fasting-mimicking diet drives anti-tumor immunity against colorectal cancer by reducing IgA-producing cells”
This preclinical study reveals the mechanisms for how FMD works. The results are very positive. It’s technical but if you read the abstract and the discussion sections, you’ll get a good understanding of why they believe FMD works and how it might benefit cancer patients. Note: After you use this link to the study, click the PDF link for the full write-up.
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Calorie restriction such as intermittent fasting and FMD are robust interventions for cancer prevention
In a recent report, the American Cancer Society suggests intermittent fasting may be an option for overweight and obese people trying to reduce their cancer risk, but they want more research data before they will support its use for cancer patients including cancer patients who have completed therapy.While that is their final recommendation, this report also states, “Several observational studies and a few small clinical trials suggest that prolonged fasting in selected patients with cancer who receive chemotherapy may be safe, feasible, and potentially capable of decreasing chemotherapy-related toxicity and tumor growth.”
In addition, there are several citations of successful animal studies and its opening statement says, “Calorie restriction (CR) without malnutrition remains the most robust intervention to date for cancer prevention in rodents and monkeys, and, in humans, it promotes anticarcinogenic adaptations such as decreased production of growth factors, inflammatory cytokines, and anabolic hormones as well as decreased oxidative stress and free-radical–induced DNA damage.”
Fasting Details
The caveat? A lot of the research evidence is pre-clinical (not human studies). The medical community won’t add fasting into standard clinical care unless it is proven in a phase III trial. Early studies in humans are promising, but large phase III clinical trials involving food/diet is extremely difficult to pull off because people have a hard time consistently sticking to a diet and following directions (surprised?). Stay tuned for more information because several phase I and II clinical trials are underway— see the clinical trials to the right.
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Research indicates that intermittent fasting of 12-13 hours per day is a safe and potentially beneficial strategy for cancer patients.
In addition, Dr. Valter Longo suggests a 12 hour fast in his interview with Rich Roll: Interview with Dr. Valter LongoWhen you eat is important: Several experts note optimization of fasting benefits can occur by aligning with circadian rhythm; concentrate eating earlier in the day and no eating later than around 7 pm. In fact, research suggests that some molecular benefits of intermittent fasting will not occur if late night eating occurs, even if the total hours fasted remains the same.
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The FMD is a 5 day program. It is only available through Prolon, a company founded by Dr. Valter Longo. Click here to purchase the FMD. It is important to know that you cannot recreate this diet on your own. Each daily food package has been especially formulated to achieve a specific metabolic response.
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In 2021, “Safety and Feasibility of Fasting-Mimicking Diet and Effects on Nutritional Status and Circulating Metabolic and Inflammatory Factors in Cancer Patients Undergoing Active Treatment” was published in Cancers magazine. It included 90 patients and FMD was administered every 3 weeks with an averageof 6.3 cycles/patient.
“Our trial showed that, when combined with dietary and muscle training instructions to promote weight and lean body mass re-gain in the periods between FMD cycles, even multiple administrations of this dietary regime were safe in cancer patients at low nutritional risk.
The FMD decreased fat mass and effectively lowered the circulating insulin, IGF1 and leptin.”
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Some clinical trials are underway. Can’t wait for the results or reports? Contact the lead researcher with questions. The lead physician and their associated organization can be found in the clinicaltrials.gov trial information. I’ve found most researchers are happy to talk to patients about their work.
Here are a few:
Fasting Mimicking Diet Program to ImpRovE ChemoTherapy in Hormone Receptor Postive (HR+), HER2- Breast Cancer (DIRECT-2): Link to # NCT05503108
Feasibility of Fasting & Exercise in Pts With HR+ MBC: Link to #NCT04708860
Fasting and Nutritional Therapy in Patients With Advanced Metastatic Prostate Cancer: Link to #NCT02710721
Characterization of Metabolic Changes in the Glioma Tumor Tissue Induced by Transient Fasting (ERGO3) (ERGO3): Link to #NCT04461938
A Case Crossover Study of Intermittent Fasting in CLL/SLL: Link to #NCT04626843
Intermittent Fasting and CLL/SLL: Link to #NCT04626843
Who might benefit?
Intermittent Fasting
Cancer patients trying to prevent recurrence
People who are overweight or obese and trying to prevent cancer
Fasting-Mimicking Diet
Triple Negative Breast Cancer
Colorectal Cancer including KRAS-mutated
Pancreatic adenocarcinoma
Small-cell lung cancer
Leukemia (see Starving Leukemia)
Cancer patients trying to optimize chemotherapy results
In addition, Dr. Longo believes there may be benefit for cancer patients on a much broader scale. He is helping researchers conduct clinical trials to learn more; several clinical trials are underway using a combination FMD plus chemotherapy treatment. Visit clinicaltrials.gov to find a study that might be right for you.
Talk to your doctor. Research suggests that overweight and obese patients may benefit from a medically-managed fasting protocol, but it is important for all cancer patients to maintain lean body mass because it is associated with superior overall cancer survival.
Talk to your doctor to find out if fasting is a good strategy for you. Do your research and bring in the evidence. Discussion and engagement is good.
My Story
When I was first diagnosed as metastatic, I made some drastic diet changes (vegan plus fish) because I believed food could help me or hurt me. At the time, I didn’t have the detailed information I have now suggesting fasting can enhance chemotherapy, but I was engaged in a calorie restricted diet. I did have a complete pathological response (no cancer) from the chemotherapy and I continue to be disease-free three years later while taking the standard protocol of trastuzumab, perjeta, and an aromatase inhibitor.
I absolutely believe the drugs are doing the heavy lifting to kill cancer cells, and I try to help the drugs as much as possible. I eat according to a circadian clock (not after 7 pm) and I make sure I get 12-13 hours of fasting per day to give my body time to repair itself. I have tried the Fasting Mimicking Diet, but since I had already completed chemotherapy by the time I learned about it, I’ve only done it once. I thought it was fairly easy to adhere to it and I really liked the daily online coaching that comes with the product. Since I currently don’t have evidence of disease, I’m waiting for more data to come out before considering its regular use. I encourage you to watch as many podcasts with Dr. Valter Longo as possible. I believe in his integrity and that he is pursuing this research to improve mankind. FYI, he donates all proceeds from his book, Longevity Diet, to further research. Impressive.
Do your own research, too.
This website highlights some particularly compelling research studies but I encourage you to do your own research. Often your medical center has a library with wonderful librarians that are happy to help and with full access to all the latest information.