Fasting 13 Hours or More at Night Reduce Breast Cancer Recurrence Risk

The prevalence of breast cancer among women is high, which makes it a common cause of death in them. The incidence of breast cancer is more common among women in developing countries.    

There are several factors responsible for the recurrence of breast cancer in women due to its nature of being a multifactorial disease. A healthy diet is presumed generally to have improved outcomes for breast cancer, yet, the data available indicates mixed evidence. The main focus of the researchers has been upon the type of food that cancer patients can prevent that includes specific types and groups of foods or patterns of diet.

Growing evidences suggest that not only the type of food that cancer patients eat affects their body, but along with that, the time at which they take food also affects their metabolic health and their state of cancer.

Researchers carried out animal studies reporting that in the mouse, there was arrest in the progression of the tumor when there were two 48-hours cycles of fasting alone. Additionally, for the incurable tumor in humans, in the animal model, survival was long-term and disease-free with a combination of chemotherapy with fasting. This survival could be the synergistic effect that cannot be achieved alone, either with only chemotherapy or fasting.

A study (1) analyzed the association of biomarkers of breast cancer risk, especially HBA1c, with the fasting duration of nighttime among women. The purpose of the study was to determine whether any association exists between prolonged nightly fasting and reduced prostaglandins and HBA1c concentrations and their role in reducing the risk of breast cancer.

The analysis shows that a glucose measurement at every 2-hour reduced by 4% as well as the level of HBA1c for every nightly fasting increased by 3-hours. The study suggests that there is a significant association of improved glycemic regulation with longer fasting duration at nighttime.

In another study (2), women who fasted for less than 13 hours per night were compared with women who fasted for more than 13 hours per night to predict the recurrence of breast cancer in women.

The analysis shows that there is a 36% increase in the risk for recurrence of breast cancer in women who fasted for a short duration during nighttime that is less than 13 hours per night. However, lower levels of HBA1c were observed with longer durations of fasting during nighttimes.

There are metabolic implications when the sleep-wake cycles are synchronized with schedules of feeding-fasting on daily basis. Glucoregulation also improves as a result of positive changes in metabolism which is associated with fasting during nighttime. A feasible and simple strategy could be to increase the duration of the fasting period during nighttime. This can help in reducing the recurrence of breast cancer. 


1.         Marinac CR, Natarajan L, Sears DD, Gallo LC, Hartman SJ, Arredondo E, et al. Prolonged Nightly Fasting and Breast Cancer Risk: Findings from NHANES (2009–2010). Cancer Epidemiol Prev Biomark. 2015 May 1;24(5):783–9.

2.         Marinac CR, Nelson SH, Breen CI, Hartman SJ, Natarajan L, Pierce JP, et al. Prolonged Nightly Fasting and Breast Cancer Prognosis. JAMA Oncol. 2016 Aug 1;2(8):1049–55.