Women over the age of 50 who lose weight — even as little as 4 lbs. — and keep it off may lower their risk of developing breast cancer, a new study finds.
This research, published in the Journal of the National Cancer Institute, is an important new development and one of the largest studies to find a significant link between weight loss and a reduced risk of breast cancer. It also echoes older research that found that obesity increases the chance of breast cancer after menopause.
“We’re so thankful to be able to say it’s not too late to lower your risk if you’ve previously gained weight, even after age 50,” study co-author Lauren Teras, scientific director of epidemiology research at the American Cancer Society, told Time.
The wide-ranging study used data from 10 different previous studies. In total, the researchers looked at the health histories of 180,000 women over 50 from the U.S., Australia and Asia for a decade, and looked at how their weight changed from the beginning, middle and end of the study, and if they were diagnosed with breast cancer. Almost 7,000 of the women developed breast cancer over the course of a decade.
After adjusting for other obesity and breast cancer risk factors, the researchers found that losing weight and keeping it off had a significant impact on the chance of developing breast cancer.
Those who lost just 4.5 lbs. lowered their risk by about 18 percent, and it only improved from there — women who lost 20 lbs. and kept it off reduced their risk by around 32 percent.
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“What we found was that indeed, women who lost weight and kept it off had a lower risk of breast cancer than women who stayed the same weight,” Teras told NBC News.
The results were more significant for women who started the study overweight, Teras added to Time, and those at a healthy weight do not need to lose weight, she said. But the study results are significant considering that about 70 percent of American adults are overweight or obese.
The study’s results do not show cause and effect, Teras said, and more research is needed, but she believes that the change in hormone levels when losing weight is a likely factor.