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Fasting at Night May Lower Breast Cancer Recurrence

An intriguing new study for early-stage breast cancer survivors

Fasting at Night May Help Breast Cancer Survivors

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The study found that fasting at night may help reduce the risk of recurrence in women with early-stage breast cancer.

En español | Breast cancer research has long emphasized what cancer survivors should eat to stay healthy, but an intriguing new study says it may have more to do with how much they don’t eat — specifically at night.

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The study, published March 31 in JAMA Oncology, found that not eating for 13 hours between dinner and breakfast may help reduce the risk of recurrence in women with early-stage breast cancer.

It’s not clear exactly why fasting would have this effect, but researchers noted that with every additional two hours of fasting, women’s average blood sugar went down and their hours of sleep increased. Better sleep quality and lower glucose could affect risk for disease.

Researchers looked at data for 2,413 women, average age 52. None of the women had diabetes, but they had been diagnosed with early-stage breast cancer between the ages of 27 and 70.

After seven years of follow-up, the study found that the women who fasted for less than 13 hours overnight had a 36 percent higher risk for breast cancer recurrence compared with those who fasted for more than 13 hours. There was no link, however, between a shorter fasting time and death from breast cancer or other causes.

Such a “novel and simple strategy to reduce breast cancer recurrence,” as the authors wrote, holds great appeal to many cancer survivors.

However, lead author Ruth Patterson of the University of California, San Diego, cautioned that the study doesn’t mean that nightly fasting should be followed to keep cancer from coming back.

“Among generally healthy adults, there are no apparent risks of extending the nightly fasting interval and it could potentially improve metabolic health and/or sleep patterns,” she told AARP in an email. But the findings are still “too premature” to make them a public health recommendation at this point.