What is the connection between chemotherapy and fasting?

A number of my patients receive both the convention approach to cancer and the naturopathic approach, so that we can support a person’s body as they go through chemotherapy.  One of the tactics that we can use is fasting.

There is research that shows that people who fast during chemotherapy have a better outcome. I think this is important research that should be spread and told to people undergoing chemotherapy because we can actually improve the results of chemotherapy agents with this tactic.

Chemotherapy can be effective at breaking down cancer cells and tumours, but the challenge is that chemotherapy can also be quite toxic on the body. Now if you incorporate fasting while doing chemotherapy decreases the toxic effects of the chemotherapy agent.

Fasting helps to decrease the side effects of chemotherapy.

Fasting can delay the growth of some cancer cells.

Fasting done with chemotherapy has been shown to be protective of normal cells. Often normal cells are damaged with chemotherapy, but with fasting during chemotherapy, we can be some protection of the normal, healthy cells.

Fasting with chemotherapy has been shown to potently sensitize cancer cells to the chemotherapy agent. So it actually helps that chemotherapy agent to work more effectively, when a person has fasted.

It was also been shown that fasting with chemotherapy significantly increases survival rates.

How do we do fasting with chemotherapy?

You need to be doing a water fast. So you are only consuming water.

You are fasting 2-3 days prior to receiving chemo and continuing to fast for at least 24 hours after receiving that chemotherapy agent. That timeline of fasting following chemo is dependent of the half-life of the chemotherapy agent. Therefore if the half-time of the chemotherapy agent is 36 hours that you need to fast for 36 hours after receiving the chemotherapy agent.

In summary you are water fasting 2-3 days prior to receiving chemo and 1-2 days after receiving chemo and this will actually help the chemotherapy agent to work more effectively.


Lee C, Raffaghello L, Brandhorst S, et al. Fasting cycles retard growth of tumors and sensitize a range of cancer cell types to chemotherapy. Science translational medicine 2012;4:124ra27. [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3608686/]