Written by Dr. Nathan Gershfeld, D.C., founder of Fasting Escape and former staff doctor at True North Health Center.
Cancer is a topic that requires honesty. I am not going to tell you that water fasting cures cancer. What I can tell you is that the research on fasting and cancer is genuinely compelling, that fasting has a meaningful role both as a complement to conventional treatment and as a prevention strategy, and that the mechanisms behind these effects are real and increasingly well understood.
What the Research Shows
The relationship between fasting and cancer has been one of the most active areas of research in oncology over the past two decades. Several important findings have emerged.
Fasting and chemotherapy:
Research from Dr. Valter Longo at the University of Southern California has shown that short-term fasting before and during chemotherapy can protect healthy cells from the toxic effects of treatment while simultaneously making cancer cells more vulnerable. Normal cells respond to fasting by entering a protective mode. Cancer cells, which have lost the ability to regulate their own growth, cannot make this shift and become more susceptible to chemotherapy damage. This differential stress response has been demonstrated in multiple cancer types in both animal and human studies.
Autophagy and cancer prevention:
Extended fasting activates autophagy — the cellular cleaning process — at levels that shorter fasting protocols cannot produce. Autophagy clears damaged proteins, dysfunctional organelles, and cellular debris that can contribute to cancer development over time. Regular activation of deep autophagy through extended fasting is one of the most direct ways to reduce the accumulation of cellular damage that precedes cancer.
Insulin and IGF-1 reduction:
Fasting dramatically reduces insulin and insulin-like growth factor 1 (IGF-1), both of which are associated with cancer cell growth and proliferation. High insulin and IGF-1 levels create an environment that encourages cancer cells to grow. Fasting creates the opposite environment — one that is hostile to cancer cell growth and supportive of normal cell health.
Immune system reset:
Research has shown that extended fasting triggers regeneration of immune cells, including the immune cells responsible for identifying and destroying cancer cells. A renewed and better-functioning immune system is one of the body’s most important defenses against cancer.
The True North Health Foundation lymphoma case studies:
Some of the most compelling clinical evidence on fasting and cancer comes from published case studies out of the True North Health Foundation. Two peer-reviewed case reports document the remission of stage IIIa, grade 1 follicular lymphoma in a 42-year-old woman who underwent a 21-day medically supervised water-only fast followed by an exclusively whole plant food diet. The first case report, published in BMJ Case Reports in 2015, documented remission at six and nine-month follow-up. The second, published in 2018, showed continued remission three years later confirmed by CT and PET scan imaging. A subsequent case series published in 2024 documented three additional patients with low to intermediate grade follicular lymphoma who each experienced reduction in the size and metabolic activity of lymph nodes following one or more prolonged water-only fasting interventions, with results independently confirmed by their oncologists. These are not anecdotes. They are peer-reviewed published case reports providing substantial rationale for continued research on the efficacy of water-only fasting for low-grade follicular lymphoma.
Fasting as a Complement to Conventional Treatment
I want to be clear about what I mean when I say fasting can complement cancer treatment, because the answer depends on the type of cancer.
For cancers where conventional treatment — surgery, chemotherapy, radiation, or immunotherapy — produces outcomes significantly better than watchful waiting, fasting and a healthy lifestyle are a powerful complement. They create a better biological environment, support immune function, reduce insulin and IGF-1, and in the case of chemotherapy may increase treatment effectiveness while protecting healthy tissue.
For cancers where research shows that conventional treatment offers little meaningful advantage over watchful waiting, fasting becomes one of the most valuable primary tools available. In these situations, optimizing the body’s internal environment through fasting, diet, and lifestyle is not a consolation — it is a serious and evidence-informed strategy.
Knowing which category your cancer falls into is a conversation to have with your oncologist. What I can offer is the fasting side of that equation, and I work closely with the rest of your care team to make sure the approach is appropriate for your specific situation.
Fasting for Cancer Prevention
For people who have not been diagnosed with cancer but are thinking about long-term health and disease prevention, the case for periodic extended fasting is strong.
The mechanisms are straightforward. Fasting reduces the chronic elevated insulin and IGF-1 that promote cellular growth and proliferation. It activates autophagy that clears pre-cancerous cellular damage. It supports immune function. And it produces the kind of metabolic reset that reduces the systemic inflammation that underlies many chronic diseases including cancer.
People who are overweight, have insulin resistance, or have a family history of cancer have particular reason to take fasting seriously as a prevention strategy. Excess body fat, chronically elevated insulin, and systemic inflammation are among the most significant modifiable cancer risk factors — and extended water fasting addresses all three directly.
What I Do at Fasting Escape
At Fasting Escape I work with two groups of people when it comes to cancer.
The first group is people who have completed cancer treatment and are looking to support their recovery, rebuild their immune system, reduce their risk of recurrence, and address other health conditions that may have developed alongside or during treatment.
The second group is people who have not had cancer but are focused on prevention — reducing their risk through the metabolic and cellular benefits that extended fasting produces.
I do not work with people who are currently undergoing active cancer treatment without close coordination with their oncology team, and even then only in situations where the clinical picture clearly supports it.
Every program begins with an initial consultation where we review your health history, your current situation, and what you are hoping to achieve. If fasting is appropriate for you, we determine the right program. If it is not appropriate, I will tell you clearly.
Book your initial consultation here
Frequently Asked Questions
Can water fasting help with cancer?
The research shows that fasting can complement conventional cancer treatment by creating a more favorable biological environment, and supports cancer prevention through autophagy activation, insulin reduction, and immune system support. It is not a cancer cure and is not a replacement for conventional oncological care.
Does fasting help during chemotherapy?
Research from Dr. Valter Longo and others suggests that short-term fasting before and during chemotherapy may protect healthy cells while making cancer cells more vulnerable to treatment. This should only be considered in close coordination with your oncology team.
How does fasting prevent cancer?
Fasting reduces insulin and IGF-1, activates autophagy that clears damaged cellular components, supports immune function, and reduces systemic inflammation — all of which are directly relevant to cancer risk reduction.
Can I fast if I have cancer?
This depends entirely on your specific situation, treatment status, and health history. It requires careful evaluation and close coordination with your oncology team. The initial consultation at Fasting Escape is where we assess whether fasting is appropriate for your situation.
How long should a fast be for cancer prevention?
For prevention purposes, fasts of one to two weeks periodically produce meaningful autophagy activation, immune renewal, and metabolic reset. The appropriate duration for your specific situation is determined during the initial consultation.
Water fasting can help with many other chronic health conditions. See all the conditions we work with at Fasting Escape.
Written by Dr. Nathan Gershfeld, D.C. Doctor of Chiropractic with 14 years of clinical experience in fasting and natural health. Dr. Gershfeld spent 6 years at the True North Health Center as an intern and staff doctor, then founded Fasting Escape, first as an in-person fasting clinic and now as a remote program bringing doctor-supervised fasting to people at home.