In this blog, we’re diving into how fasting might help in the fight against cancer. That said, it’s really important to check in with your doctor or a trusted healthcare professional before trying any fasting routine. Fasting can be a great tool for some, but in certain situations, it could actually do more harm than good, so it’s always best to get the green light first. Fasting can produce many benefits, however, today we are looking at its use and impact for cancer prevention and treatment.
Fasting has emerged as a powerful tool in both cancer prevention and integrative recovery strategies. Supported by a growing body of scientific evidence, fasting is far more than a wellness trend—it’s a potent metabolic practice that can enhance your body’s natural defenses and resilience during cancer treatment. Additionally, fasting holds significant spiritual value, mentioned frequently throughout Scripture as a practice for healing, spiritual renewal, and deepening one’s relationship with God.
In this post, we’ll explore what the research says about fasting for cancer, including how it works, key types of fasting, and what to consider before trying it.
What Is Fasting?
Fasting is the voluntary abstention from food for a specific period. Several types of fasting protocols have been studied for cancer:
- Intermittent Fasting (IF): Alternating periods of eating and fasting (e.g., 16:8 daily or 5:2 weekly).
- Time-Restricted Eating (TRE): Consuming all meals within a shortened window, typically 8–10 hours.
- Prolonged Fasting: Extended fasts lasting 24 hours or more.
- Fasting-Mimicking Diet (FMD): A low-calorie, plant-based regimen designed to mimic the effects of fasting while providing nutrients.
Fasting for Cancer Prevention
Supports Cellular Repair through Autophagy
Fasting triggers autophagy, a process where the body clears out damaged cells and recycles components, helping to prevent mutations that can lead to cancer.
> Scientific Insight: Autophagy and improved DNA repair mechanisms are enhanced by caloric restriction and fasting (Madeo et al., Nature Reviews Cancer, 2016).
Reduces IGF-1 and Insulin Levels
High insulin and insulin-like growth factor 1 (IGF-1) levels are associated with increased cancer risk. Fasting helps to reduce these growth signals.
> Key Study: Fasting has been shown to lower IGF-1 and increase longevity in animals and humans (Longo & Fontana, Science Translational Medicine, 2010).
Decreases Inflammation and Oxidative Stress
Chronic inflammation is a driver of many cancers. Fasting can reduce inflammatory markers and oxidative damage.
> Clinical Evidence: Intermittent fasting improved inflammation markers in humans (de Cabo & Mattson, NEJM, 2019).
Fasting During Cancer Treatment
May Reduce Chemotherapy Side Effects
Animal studies and early human trials suggest that fasting before chemotherapy can reduce nausea, fatigue, and other side effects.
> Pilot Study: Patients fasting for 48–72 hours around chemo cycles reported fewer side effects (Safdie et al., Aging, 2009).
Protects Healthy Cells While Targeting Cancer Cells
This concept—called differential stress resistance—suggests that healthy cells become more resilient during fasting, while cancer cells remain vulnerable.
> Animal Evidence: Fasting reduced toxicity and improved outcomes in mice undergoing chemotherapy (Raffaghello et al., PNAS, 2008).
Fasting-Mimicking Diet (FMD)
The FMD, created by Dr. Valter Longo, provides the benefits of fasting while still allowing some food intake.
> New Study: A 2020 Nature Communications study found that FMD cycles delayed tumor growth and reduced cancer risk markers in animal models. Early clinical research suggests it’s a promising adjunct to conventional therapy.
Important Considerations
Fasting is not for everyone. It is not recommended for individuals who are:
- Underweight or experiencing malnutrition
- Suffering from cachexia or muscle wasting
- Managing diabetes or other metabolic conditions without supervision
- Undergoing active treatment without guidance from a health professional
Always consult your healthcare provider before beginning a fasting regimen, especially during cancer treatment.
Conclusion
Fasting—whether through intermittent fasting or structured fasting-mimicking diets—holds exciting promise in both reducing cancer risk and supporting treatment outcomes. While more large-scale human trials are underway, current evidence suggests fasting can:
- Promote autophagy
- Lower inflammation and insulin
- Enhance chemotherapy outcomes
- Protect healthy cells
As research continues, fasting may become a key part of integrative cancer care.
Healthy Wishes
Wally Bishop I.N.H.C., C.N.C., C.I.C.P.
Board Certified Holistic Health Practitioner
Board Certified Functional Nutrition Coach
The contents of this blog is not and should not be considered medical advice. This blog is for informational purposes only. Always consult with your doctor before making any dietary or lifestyle changes. Never quit taking prescription medications unless advised to do so by your doctor.
References
- Madeo F, Pietrocola F, Eisenberg T, Kroemer G. Nature Reviews Cancer. 2016.
- Longo VD, Fontana L. Science Translational Medicine. 2010.
- de Cabo R, Mattson MP. New England Journal of Medicine. 2019.
- Raffaghello L et al. PNAS. 2008.
- Safdie FM et al. Aging (Albany NY). 2009.
- Di Biase S et al. Nature Communications. 2020.
Biblical References for Fasting
- Matthew 6:16-18–
“When you fast, do not look somber as the hypocrites do… so that it will not be obvious to others that you are fasting, but only to your Father…”
- Isaiah 58:6–
“Is not this the kind of fasting I have chosen: to loose the chains of injustice… and to set the oppressed free…”
- Joel 2:12–
“Even now,” declares the Lord, “return to me with all your heart, with fasting and weeping and mourning.”
- Ezra 8:23–
“So we fasted and petitioned our God about this, and he answered our prayer.”
- Acts 13:2-3–
“While they were worshiping the Lord and fasting, the Holy Spirit said, ‘Set apart for me Barnabas and Saul…’ So after they had fasted and prayed, they placed their hands on them and sent them off.”
- Luke 4:1-2–
“Jesus, full of the Holy Spirit… was led by the Spirit into the wilderness, where for forty days he was tempted by the devil. He ate nothing during those days…”
- Daniel 10:3–
“I ate no choice food; no meat or wine touched my lips; and I used no lotions at all until the three weeks were over.”
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