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Intermittent Fasting & Cancer

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Intermittent fasting & cancer, or I should say intermittent fasting during chemotherapy offers real potential as an evidence-based non-conventional therapy but, as always, the devil is in the details.

The purpose of the post is to brief cancer patients looking into this form of complementary therapy. I’ve been researching and posting about intermittent fasting for cancer for years now. The problem has always been that studies point to theoretical benefits but I’ve never found studies to support specific types of cancer benefiting from intermittent fasting during chemotherapy.

The third study linked and excerpted below talks about fasting, breast cancer and quality of life benefits. Improvements in QOL is great but I’m looking for studies about intermittent fasting enhancing the efficacy of chemotherapy.

The pros and cons of intermittent fasting & cancer- 

Short-term fasting, also known as intermittent fasting, is a dietary approach that involves alternating periods of eating with periods of fasting. There has been growing interest in the potential benefits of short-term fasting in combination with chemotherapy, but it’s important to note that this area of research is still evolving, and individual responses can vary. Here are some potential risks and benefits associated with short-term fasting during chemotherapy:


  1. Enhanced Sensitivity of Cancer Cells to Treatment:
    • Some studies in animal models have suggested that short-term fasting may sensitize cancer cells to the effects of chemotherapy, potentially making the treatment more effective.
  2. Reduced Side Effects:
    • Fasting may help reduce certain side effects of chemotherapy, such as nausea, vomiting, and fatigue, although more research is needed to establish this connection.
  3. Protection of Healthy Cells:
    • Fasting may induce a state of cellular protection, where normal cells become more resistant to the toxic effects of chemotherapy drugs, potentially reducing damage to healthy tissues.
  4. Improved Immune System Function:
    • Some research indicates that short-term fasting can enhance immune system function, which may help the body better tolerate and respond to chemotherapy.
  5. Metabolic Benefits:
    • Fasting can lead to changes in metabolic pathways, including increased insulin sensitivity and improved blood sugar regulation, which may be beneficial for cancer patients.

Risks and Considerations:

  1. Nutrient Deficiency:
    • Fasting, especially if done for extended periods, can lead to nutrient deficiencies. This can be a concern for cancer patients who need adequate nutrition to support their immune system and overall health.
  2. Weight Loss:
    • Fasting can lead to weight loss, which may not be desirable for some cancer patients, especially those who are already underweight or struggling with appetite.
  3. Potential for Increased Toxicity:
    • Some chemotherapy drugs have specific dosing schedules that are optimized for maximum efficacy with minimal toxicity. Fasting might alter the pharmacokinetics of these drugs, potentially leading to unintended consequences.
  4. Individual Variations:
    • Responses to fasting can vary widely among individuals. What works for one person may not work for another, and some patients may not tolerate fasting well.
  5. Lack of Long-term Studies:
    • The long-term effects of combining short-term fasting with chemotherapy are not yet well-understood. It’s essential to approach this approach with caution until more comprehensive research is available.

I need to point out that the study about breast cancer and intermittent fasting uses a chemotherapy regimen that is quite toxic and can cause serious short, long-term and last stage side effects. I say this because I have also undergone a chemo called adriamycin and I have sustained the side effect called chemotherapy-induced cardiomyopathy as a result.

Have you been diagnosed with cancer? What type? What stage? To learn more about cancer and nutrition, please contact me at David.PeopleBeatingCancer@gmail.com.

David Emerson

  • Cancer Survivor
  • Cancer Coach
  • Director PeopleBeatingCancer

10 Evidence-Based Health Benefits of Intermittent Fasting

“Intermittent fasting may benefit heart health, reduce inflammation, and improve cell repair processes. It may also help burn fat.

Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting.

There are many different types of intermittent fasting, such as the 16/8 and 5:2 methods.

Numerous studies show that it can have powerful benefits for your body and brain.

Here are 10 evidence-based health benefits of intermittent fasting…”

Current Evidence and Directions for Intermittent Fasting During Cancer Chemotherapy

“Available data show that periodic fasting, a form of intermittent fasting, may hold potential to improve the effectiveness of chemotherapy, decrease treatment-related side effects and cancer-promoting factors such as insulin, while ameliorating treatment-related decreases in quality of life and daily functioning…

Conclusion- Preliminary human studies exploring the potential of intermittent fasting as a nutrition therapy during chemotherapy to improve treatment and patient outcomes are limited yet promising. Short-term fasting and the fasting mimicking diet may decrease treatment-related side effects, improve quality of life, and decrease insulin compared with the current standard care. Further, if the changes in insulin promote improved insulin sensitivity these periods of nutrient deprivation may improve the efficacy of chemotherapy treatment.

Fasting During Breast Cancer Chemo Improves Quality of Life

“Short-term fasting during chemotherapy enhances health-related quality of life in patients with early breast cancer, with no untoward effects, according to late-breaking research presented on day 1 of the European Society for Medical Oncology (ESMO) Congress 2023.

“Strikingly,” fasting also appeared to prevent fatigue, something patients with breast cancer struggle with…

The study adds to other evidence suggesting that fasting around chemotherapy cycles may reduce toxicity and adverse effects associated with chemotherapy…

“Short-term fasting in subjects not at risk for malnutrition is feasible, well tolerated, and appears to improve several parameters of quality of life,” Arends said…

The chemotherapy regimens in the trial included four cycles of adriamycin or epirubicin, followed by taxane therapy. The interventions for both groups occurred about 2 days before chemotherapy plus 24 hours after each cycle ended (about 60-72 hours total).

For the fasting group, this meant about 200 kcal/d through vegetable juices and vegetable broths. In between chemotherapy sessions, both groups were advised to eat a more vegetarian-focused diet, but that was not mandatory…

Although the two groups “started out from the same point, the fasting group had an incremental effect, which quite startled us,” Koppold told the audience. “Over the course of the chemotherapies, [fasting] had additive effects” and by cycle four of chemotherapy, the difference became statistically and clinically significant, indicating “much better” quality of life in short-term–fasting group…”





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