Intermittent Fasting for Breast Cancer Recurrence Prevention

I’m very excited to start discussing real topics that come up during my practice. Please check back under the Q and A section frequently for more real world topics.

A patient asked me about a topic I was completely unaware. She asked if anyone who has had a personal history of breast cancer should start doing a 16 hour fast.

Until researching this topic, I actually had not heard of fasting in dealing with cancer.

I discovered that there could be some benefits from Intermittent Fasting in terms of Breast Cancer Survivor-ship. There is a potential benefit from fasting while being treated for breast cancer.

Before delving too deeply into this topic, I have a few of my own caveats. I typically don’t recommend intermittent fasting in patients who don’t have a PRISTINE diet. If I have patients that are following a nutritionally sound diet, that are not diabetic, and not being treated with medications that lower their blood sugar, I think Intermittent Fasting can be beneficial.

Patients that are Diabetic likely can’t perform intermittent fasting. Several diabetic medications cause the body to release insulin in an uncontrolled manner. If you aren’t eating and take these medications, blood sugars may drop unexpectedly.

If you don’t regularly consume a healthy quantity of fruits and vegetables daily, fasting means you will become further deprived in necessary nutrients.

Photo by Miguel Á. Padriñán on

I was able to find the article, Prolonged Nightly Fasting and Breast Cancer Prognosis. This link will take you the article which can be accessed by the public. Breast cancer survivors were asked to keep track of their diets for up to 4 years. The researchers collected data on how long these women fasted overnight. The researchers discovered that women that fasted less than 13 hours per night had an increased risk of breast cancer recurrence.

“…prolonging the length of the nightly fasting interval could be a simple and feasible strategy to reduce breast cancer risk recurrence”

Marinac CR, Nelson SH, Breen CI, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016;2(8):1049–1055. doi:10.1001/jamaoncol.2016.0164

This study excluded diabetic patients. Prolonged overnight fasting (ie, not eating late at night) was not associated with weight loss, but there was a drop in inflammatory markers in the blood.

I stumbled across a related article concerning short-term fasting while being treated with chemotherapy. The researchers here examined the role of short-term fasting while receiving chemotherapy. The theory here is that cancer has a higher metabolism than normal tissues, and will take up more of the chemotherapy than regular cells. Human cells tend to go into a quiet state during fasting. The researchers found that short term fast while receiving chemotherapy in certain cancer types (HER2-Negative) had less markers of DNA damage during chemotherapy treatment.

Summary and Recommendations

  • If you are a breast cancer survivor, consultation with a nutritionist can play an important role in your future care
  • If you are a breast cancer survivor, you may want to consider avoiding late night eating.
  • If you are a Breast Cancer Survivor with Diabetes, discuss with your doctor dietary changes that may prevent recurrence.
  • If you are undergoing treatment for Breast Cancer now, discuss with your Oncologist, General Surgeon, and Nutritionist if you should consider short term fasting. Keep in mind, you nutritional status affects healing, and your doctors may not wish for you to to this.


Marinac CR, Nelson SH, Breen CI, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016;2(8):1049–1055. doi:10.1001/jamaoncol.2016.0164

de Groot, S., Vreeswijk, M. P., Welters, M. J., Gravesteijn, G., Boei, J. J., Jochems, A., … Kroep, J. R. (2015). The effects of short-term fasting on tolerance to (neo) adjuvant chemotherapy in HER2-negative breast cancer patients: a randomized pilot study. BMC Cancer, 15(1).


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