Overnight Fast May Reduce Risk of Breast Cancer Recurrence

Patient Expert

Can the simple act of not snacking after dinner reduce your risk of breast cancer recurrence? It's possible.

According to a new study published this spring in the online Journal of the American Medical Association, “Prolonging the length of the nightly fasting interval may be a simple, nonpharmacologic strategy for reducing the risk of breast cancer recurrence.”

Let’s dig a little deeper into this study.

Assessing the benefits of an overnight fast

There’s never been a human study -- a.k.a., a clinical trial -- observing the potential relationship between fasting for a certain number of hours at night and breast cancer risk. However, a 2015 study did indicate prolonged fasting at night lowers a person’s risk of systemic inflammation. And since inflammation is thought to raise a woman’s risk of breast cancer, wouldn’t lowering inflammation, via nightly fasting, reduce breast cancer risk?

Catherine Marinac decided to find out. Currently a researcher at Harvard University’s T.C. Chan School of Public Health and the Dana Farber Cancer Institute, she and her fellow researchers decided to mine data from the long-term Women’s Healthy Eating and Living Study (WHEL), a National Institutes of Health-supported clinical trial stretching from 1995 to 2007.

How the study worked

Marinac and team identified 2,413 women in the study who’d been diagnosed with breast cancer. They used existing dietary data to ascertain the length of the nightly fast for each of those survivors. They then married that information with the number of women who’d experienced a breast cancer recurrence.

The result? Those women who had fasted less than 13 hours per night were 36 percent more likely to have experienced a recurrence than those who went at least 13 hours between their last food at night and their first bite the next morning.

What does this prove?

At this point, the data categorically prove … well, nothing. Since the WHEL Study wasn’t focused specifically on overnight fasting, the data gathered was based on study participants’ self-reported data -- which can be inaccurate, due to memory issues or reluctance to report true behaviors.

The next step, one that would produce truly reliable results, would be to conduct what’s called a randomized trial, where some breast cancer survivors fast for 13 hours each night and some fast fewer than 13 hours each night. Researchers would then track the rate of recurrence for each group.

But even if that trial began today, it would be years before the results were in. Recurrence of an original breast cancer can happen 5, 10, even 20 years or more after the initial diagnosis. So proof that Marinac and her fellow researchers are making the correct assumption about the relationship between an overnight fast and breast cancer recurrence would emerge far in the future, if ever.

How can you use this news?

Starting now, how difficult would it be for you to wait 13 hours between your last food at night and your first in the morning? For most of us, it would simply mean not snacking after dinner, or eating a somewhat later breakfast. And for many of us, that would be a pretty straightforward task.

As Marinac et. al. concluded, fasting “may be a simple, nonpharmacologic strategy for reducing the risk of breast cancer recurrence.”

Possibly lower my breast cancer risk by ditching the after-dinner snacks? I can do that. And so can you.

See More Helpful Articles:

Eating Right: 10 Foods for Healthy Breasts

Body Weight and Breast Cancer Risk: a New Way to Eat

Can Olive Oil Help Prevent Breast Cancer?

A Guide to Survivorship: Life After Treatment

Top 10 Breast Cancer Risk Factors

Risks and Benefits: Understanding the Statistics That Affect You

Fear of Recurrence: Where Do You Stand?


Marinac, C. R. (2016, March 31). Prolonged Nightly Fasting and Breast Cancer Prognosis. Retrieved June 18, 2016, from http://oncology.jamanetwork.com/article.aspx?articleid=2506710

"Can Fasting 13 Hours or More at Night Reduce Recurrence Risk?" (2016, April 19). Retrieved June 18, 2016, from http://www.breastcancer.org/research-news/can-fasting-reduce-recurrence-risk

Breast cancer survivor and award-winning author PJ Hamel, a long-time contributor to the HealthCentral community, counsels women with breast cancer through the volunteer program at her local hospital. She founded and manages a large and active online survivor support network.