A study published in JAMA Oncology claims that fasting more than 13 hours each night may reduce breast cancer risk for women with early-stage breast cancer. It turns out that fasting increases the chances of breast cancer recurrence by up to 36 percent.

The researchers speculate that this habit prevents factors that can cause negative cancer outcomes such as abnormal glucose metabolism, weight gain and inflammation.  Still, the research team asserts that this only shows the association and more studies are needed to verify that fasting can actually reduce the risk of breast cancer recurrence.

The researchers analysed data from the Women’s Healthy Eating and Living study conducted between 1995 and 2007. This composed of 2,413 non-diabetic women with early-stage breast cancer, who were diagnosed at 27 to 70 years.

Woman undergoing a mammogram of the right breast. Photo from Wikipedia/National Cancer Institute

A woman undergoing a mammogram of the right breast. Photo from Wikipedia/ National Cancer Institute

On the average, the women fasted for 12.5 hours each night.  Based on a follow-up more than seven years later, the research team found that fasting for less than 13 hours increased the risk for breast cancer recurrence. However, this fasting time did not increase the risk of dying from breast cancer or other causes.

Additionally, each two hours spent for fasting was related to lower levels of lower haemoglobin A1c. This also helped women sleep longer.

The researchers point out that this fasting time data were only self-reported. This would mean that some participants could have underreported or overestimated the actual time they spent for fasting.

“Our study introduces a novel dietary intervention strategy and indicates that prolonging the length of the nightly fasting interval could be a simple and feasible strategy to reduce breast cancer recurrence…given the associations of nightly fasting with glycemic control and sleep, we hypothesize that interventions to prolong the nightly fasting interval could potentially reduce the risk of type 2 diabetes, cardiovascular disease and other cancers,” conclude the study authors.