“Fasting owes its effectiveness to a basic fact of physiology. The digestive organs are the largest and bulkiest in the body, and their routine operations consume large amounts or energy, The simple act of not eating rests this system and frees up much of that energy for the body to use in healing.”   -Randi Fredricks, author of  Fasting: an exceptional human experience

Fasting has actually successfully been used as a “complementary” treatment for chemotherapy in the past. Some sort of protection against the toxicity of chemotherapy treatments was, interestingly enough, found by one study to be produced by the simple practice of intermittent fasting. This [intermittent fasting] allowed for “higher doses to be used,” consequently resulting in a more “effective” treatment.

In the article entitled “Longer Overnight Fasting May Cut Breast Cancer Recurrence: May Be a Simple Nonpharmacological Strategy,” Bruce Jancin wrote about intermittent fasting’s effect on preventing breast cancer recurrence. “Breast cancer survivors who typically didn’t eat for at least 13-hours overnight had a 36% reduction in the risk of breast cancer reoccurrence, compared with those with a shorter duration of overnight fasting, according to a secondary analysis of the Women’s Healthy Eating and Living study presented at the San Antonio Breast Cancer Symposium,” said Jancin.

When one is sleeping, he or she is technically fasting. The average adult sleeps about seven hours a day. Thus, by not eating three hours before going to sleep and then restraining from eating for three hours after you wake up, the 13-hour fasting period would be completed.

Catherine R. Marinac, a doctoral candidate in public health at the University of California, San Diego said this: “Prolonging the length of the nighttime fasting interval may be a simple non-pharmacological strategy for reducing the risk of breast cancer reoccurrence as well as other chronic conditions with etiologic ties to breast cancer, like type 2 diabetes.”

A fairly new study done by the Women’s Healthy Eating and Living (WHEL) organization had consistent results as that of earlier studies on rodents. The results demonstrated that “intermittent fasting regimens aligned with the sleep cycle brings better glycemic control and protection against carcinogenesis.” This was all noted by Dr. Marinac.

The doctor, Marinac, showed an analysis that had been done on 2,413 non-diabetic breast cancer survivors. These survivors were participants in the study conducted by the WHEL and were subjects of multiple, highly detailed 24-hour dietary recall records. These records were acquired at baseline and completed with four years of follow-ups.

Marinac said, “The diets were very well characterized. We analyzed roughly 30,000 time-stamped dietary recalls.” A little over seven years later–7.3 years to be exact– there was another follow-up. Three hundred ninety (390) women had had recurrent breast cancer. Those who did the “prolonged night fast” for 13-hours or more “were 36% less likely to have a recurrence.”

This is “according to a Cox proportionate hazard analysis and a multivariate linear regression analysis controlling for patient demographics; calorie consumption and other dietary variables; breast cancer stage, grade, and treatment; body mass index; comorbid conditions; and sleep duration.”

Eventually, in a follow-up 11.4 years later, 329 of the women died of their breast cancer. 420 of the participants who died, suffered from “all-cause” mortality. Women that extended their overnight fast to 13-hours were 21% less likely to experience breast cancer mortality and 22% less likely to suffer and/or die from any circumstances.

“Looking for potential mechanisms to explain the observed relationship between overnight fasting duration and breast cancer recurrence, Ms. Marinac and co-investigators considered as evaluable possibilities systemic inflammation, glucoregulation, adiposity, and sleep duration. C-reactive protein levels and body mass index proved to be unrelated to recurrence risk. However, glucoregulation and sleep duration were. Women with an overnight fasting length of at least 13 hours had a significantly lower glycated hemoglobin level and slept longer than those with a shorter overnight fast. The lower HbA1c seen in women who fasted for longer at night mimics an intriguing finding from the classic mouse studies that showed fasting is related to better glycemic control, she observed.”

For more on fasting’s effect on glycogen and glycemic control, click here: The Science Behind Eating and Fasting



  1. Fredricks, Randi. Fasting: an exceptional human experience. AuthorHouse, 2013. Print.
  2. Jancin, Bruce. “SABCS: Longer Overnight Fasting May Reduce Breast Cancer Recurrence Risk.” MDedge Psychiatry, 13 Dec. 2016, www.mdedge.com/familypracticenews/article/105817/breast-cancer/sabcs-longer-overnight-fasting-may-reduce-breast.