Fasting is a widely debated topic among nutrition and medical professionals. Some agree that there is not enough evidence to support the supposed benefits of fasting, while others claim it can help the immune system fight off even the most deadly of diseases. A recent study conducted at the University of California, San Diego School of Medicine has found that increasing the amount of time spent fasting overnight can help women reduce their glucose levels and overall risk for breast cancer.

"Increasing the duration of overnight fasting could be a novel strategy to reduce the risk of developing breast cancer," Catherine Marinac, UC San Diego doctoral candidate and first author on the paper, said in a statement. "This is a simple dietary change that we believe most women can understand and adopt. It may have a big impact on public health without requiring complicated counting of calories or nutrients."

Marinac and her colleagues used the 2009-2010 U.S. National Health and Nutrition Examination Survey to assess a possible link between nighttime fasting duration with biomarkers for breast cancer risk among women. Researchers combed through heath and dietary data for 2,212 women and glucose readings for 1,066 women. Nighttime fasting duration was calculated using 24-hour food records that were provided by each female participant.

Findings revealed that women who fasted longer overnight had better control over their blood glucose concentrations. In fact, each time a woman increased her nighttime fasting by three hours, she also lowered her postprandial glucose levels by four percent. Women who reported longer periods of fasting also consumed fewer calories per day, fewer calories after 10 p.m., and fewer eating episodes. On average, women consumed five meals each day and fasted for 12 hours each night.

"The dietary advice for cancer prevention usually focuses on limiting consumption of red meat, alcohol, and refined grains, while increasing plant-based foods," explained Dr. Ruth Patterson, UC San Diego Moores Cancer Center associate director for population sciences and program leader of the cancer prevention program. "New evidence suggests that when and how often people eat can also play a role in cancer risk."

According to the American Cancer Society, fasting is associated with a type of alternative therapy known as metabolic therapy. Those who support fasting as part of the “detoxification” process say that consuming only water for a certain amount of time can remove harmful toxins and substances from the body. By fasting, they believe their bodies can now focus solely on self-cleansing and -healing.

Source: Natarjan L, Patterson R, Marinac C, et al. Prolonged Nightly Fasting and Breast Cancer Risk: Findings from NHANES (2009–2010). Cancer Epidemiology, Biomarkers & Prevention. 2015.