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Study: Can long periods of fasting protect against breast cancer recurrence?

Previous research in mice suggested that long periods of fasting provide protection against factors that are associated with a poor cancer outcome. A new study associates prolonged fasting (13 hours or more) at night with a lower risk of breast cancer recurrence, but no association between fasting time at night and mortality. While these findings are interesting, more research needs to be done to confirm them. In the meantime, breast cancer survivors should discuss any concerns about nutrition with their health care providers. 05/30/16

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Most relevant for: Breast cancer survivors.

It may also be relevant for:

men with breast cancer
people with triple negative breast cancer
people with ER/PR + cancer
people with Her2-positive cancer
people with a genetic mutation linked to cancer risk
people with breast cancer

Relevance: Medium

Strength of Science: Medium-High

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Medical Daily

Night Fasting: not eating for 13 hours or more every night may reduce risk of breast cancer recurrence
This article rates 4.5 out of 5 stars

The Telegraph

Simple night-time trick could stop breast cancer returning
This article rates 4.0 out of 5 stars

At a glance	Questions for your doctor
Findings	In-depth
Clinical trials	Limitations
Guidelines	Resources

STUDY AT A GLANCE

This study is about:

How nighttime fasting affects breast cancer recurrence and mortality.

Why is this study important?

If longer fasting at night is linked to a better breast cancer prognosis, as the study authors write, “Prolonging the length of the nightly fasting interval may be a simple non-pharmacologic strategy for reducing the risk of breast cancer recurrence.”

Study findings:

Women who reported fasting fewer than 13 hours per night had an increased risk of breast cancer recurrence compared to women who reported fasting for more than 13 hours per night.

What does this mean for me?

Everyone has a period of nighttime fasting—from their last meal or late night snack until breakfast. This study looked at the length of that interval, and suggests that late night eating, which shortens the length of the nighttime fast, is associated with breast cancer recurrence. But this study does not definitively conclude that nighttime eating results in breast cancer recurrence; only that there is an association. A large, controlled trial with patients who are randomly assigned to either the nighttime fasting group or a control group is needed to provide more definitive information and confirm this association. Additionally, no current research indicates that late night eating is associated with worse health outcomes. Based on the results of this study, lengthy nighttime fasting is not needed to prevent cancer recurrence.

Research on weight gain and late night eating has produced mixed results—researchers still do not know whether late night eating makes it easier to gain weight. However, dieticians recommend avoiding late night eating because they say it is easy to overdo eating at nighttime (eating out of boredom or stress instead of hunger, for example, and portions are not as well controlled). Ultimately, the results of this research should not stop women from eating a light snack at night when hungry.

Posted 5/31/16

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References

Marinac MR, Nelson SH, Breen CI, et al. “Prolonged Nightly Fasting and Breast Cancer Prognosis.” JAMA Oncology, Published online first on March 31, 2016.

Disclosure

FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

This article is also relevant for:

men with breast cancer
people with triple negative breast cancer
people with ER/PR + cancer
people with Her2-positive cancer
people with a genetic mutation linked to cancer risk
people with breast cancer

IN DEPTH REVIEW OF RESEARCH

Study background:

Previous work in mice that were fed a high-fat diet showed that long periods (16 hours) of fasting protected the mice from inflammation and weight gain, two factors that are associated with a poor cancer outcome. However, nothing is currently known about how long periods of fasting affect human breast cancer recurrence and mortality. Catherine Marinac and her colleagues from the University of California, San Diego and other institutions published a report in the journal JAMA Oncology looking at whether the length of time a person goes without eating at night could predict recurrence and mortality for women with (stages I-III) breast cancer.

Researchers of this study wanted to know:

Does fasting at night help prevent breast cancer recurrence and mortality?

Population(s) looked at in the study:

This research used data from 2,413 women who participated in the Women’s Healthy Eating and Living (WHEL) study. These women had early-stage breast cancer (stages I-III), did not have diabetes, and were between the ages of 27-70 years old. Their dietary assessment consisted of multiple phone calls in a three-week period when they were asked what they ate and when they ate. The women were questioned in the year they enrolled in the study (baseline), the next year, and then again two years later. All 2,413 women completed the baseline assessment, about 91% completed the assessment the next year, and about 80% completed the assessment the last year.

Study findings:

Women who reported fasting for fewer than 13 hours per night had a 36% increased breast cancer recurrence risk compared to women who reported fasting for more than 13 hours per night. This increase is modest.
No association was found between fasting time at night and mortality due to breast cancer.

Limitations:

This study used data taken from the Women’s Healthy Eating and Living (WHEL) study; researchers did not produce the questions asked from the dietary assessment, or control for other things they might have wanted to ask. Additionally, the women were asked to self-report their diets and times that they ate. Self-reporting is a definite study limitation, because, memory is not infallible—women may forget the exact time they ate—and is subject to many biases. The study also followed women for a four-year period, so whether this effect lasts over longer periods is unknown. Finally, it is unclear whether shorter nighttime fast periods are responsible for the increase in recurrence or if other lifestyle factors that accompany shorter nighttime fasting, such as alcohol consumption, amount of sleep a person gets each night, or other lifestyle choices that leads to the increase in recurrence risk play a role.

Conclusions:

While this study suggests that long periods of fasting at night are associated with protection against breast cancer recurrence, more work needs to be done to confirm this finding. A large clinical trial would also allow researchers to control for other factors, such as when the women sleep. Many previous studies have found an association in people who sleep at times that disrupt their natural circadian rhythm and an increased risk for breast cancer. Based on this study, women do not necessarily need to avoid eating a light snack at night if they are hungry.

Posted 5/31/16

Share your thoughts on this XRAYS article by taking this brief survey.

Expert Guidelines

Nutrition for people diagnosed with cancer

The National Comprehensive Cancer Network (NCCN) recommends the following for cancer survivors:

Think about your food choices and the amount of fruits, vegetables and unrefined grains you eat compared with red and processed meats, alcohol, and foods or beverages with added fat or sugar.
Think about your eating habits, including portion size, snacking, how often you eat out and the use of added fats or sugars.
All survivors should be encouraged to:
- Make informed choices about food to ensure variety and adequate nutrient intake.
- Limit refined sugars.
- Eat a diet that is at least 50% plant-based, consisting mostly of vegetables, fruit and whole grains.
- Track calorie intake; monitoring calories is an effective way to manage weight.
- Minimize alcohol to no more than one drink per day for a woman and two drinks per day for a man.
For patients desiring further dietary guidelines, the USDA approximate food plate volumes are:
- Vegetables and fruits should comprise half the volume of food on the plate
- Vegetables: 30% of plate; fruits: 20% of plate
- Whole grains: 30% of plate
- Protein: 20% of plate
Recommended sources of nutrients:
- Fast: Plant sources such as olive or canola oil, avocados, seeds and nuts, and fatty fish.
- Carbohydrates: Fruits, vegetables, whole grains and legumes.
- Protein: Poultry, fish, legumes, low-fat dairy foods, and nuts.

The Academy of Nutrition and Dietetics, the United States Office of Disease Prevention and Health Promotion and the American Institute for Cancer Research also publish expert guidelines on nutrition and health.

Updated: 12/12/2021

Questions To Ask Your Doctor

How do my eating habits affect my risk for breast cancer recurrence?
What foods, if any, are known to reduce risk of breast cancer recurrence?
How else can I reduce my risk for breast cancer recurrence?

Open Clinical Trials

The following studies focus on nutrition for people diagnosed with breast cancer:

NCT05056077: Tools To Be Fit: Tools to Improve Nutrition and Physical Activity for Cancer Survivors. This study looks at which tools work best for helping cancer survivors improve their diet and exercise.
NCT05259410: Time-Restricted Eating During Chemotherapy for Breast Cancer. This study looks at whether intermittent fasting during treatment improves treatment-related outcomes and patient-related outcomes and limits treatment-related weight gain.
NCT04365569 Evaluating the Effectiveness of an Individualized Nutrition and Physical Activity Counseling Program. This pilot study looks at whether a tailored in-person and telephone-based nutrition and exercise counseling program helps breast cancer patients improve weight and fitness and thus improves cancer outcomes.
NCT03824145: Every Day Counts: A Lifestyle Program for Women With Breast Cancer (EDC). This study examines the diet and activity, body composition, blood and quality of life in metastatic breast cancer patients from Milwaukee and Chicago.
NCT05984888: Pilot Study of a MIND Diet Intervention in Women Undergoing Active Treatment for Breast Cancer. The MIND diet is high in anti-inflammatory nutrients and limits the intake of brain-unhealthy foods (i.e., foods high in fat, red meat and sweets) that may help reduce the negative effects of cancer treatments on memory and thinking. This study investigates whether the MIND diet protects function in women with invasive breast cancer who start systemic therapies.

Visit our Featured Research Page and Research Search and Enroll Tool to find additional studies enrolling people with or at high risk for cancer.

Updated: 05/31/2024

Peer Support

The following organizations offer peer support services for people with or at high risk for breast cancer:

FORCE peer support:
- Our Message Boards allow people to connect with others who share their situation. Once you register, you can post on the Diagnosed With Cancer board to connect with other people who have been diagnosed.
- Our Peer Navigation Program will match you with a volunteer who shares your mutation and situation.
- Connect online with our Private Facebook Group.
- Join our virtual and in-person support meetings.
Other organizations that offer breast cancer support:

Updated: 05/07/2024

Find Experts

The following resources can help you locate a nutritionist near you or via telehealth

Finding nutritionists

You can find a registered dietician in your area through Eatright.org, the website for the Academy of Nutrition and Dietetics. Search for nutritionists by specialty, including "cancer," "weight management" and "heart health."

Related experts

The Livestrong at the YMCA program includes a free 12-week membership and fitness training with certified exercise experts. You can search by zip code for a program near you.