In women over age 50, losing just four pounds and keeping the weight off can lower breast cancer risk, a new study suggests.

Researchers who reviewed data from 180,000 women found the more weight a woman lost – and kept off – the lower her risk of breast cancer, according to the report published in the Journal of the National Cancer Institute.

“We’ve known for some time that excess body weight (raises the risk) of breast cancer,” said lead author Lauren Teras, scientific director of epidemiology research at the American Cancer Society. “In this study we found that losing weight and keeping it off is associated with a lower risk of breast cancer in women aged 50 and older who are not taking hormone replacement therapy. This is particularly important for women who are overweight and in the U.S. about two-thirds of women are overweight or obese.”

Women with the most sustained weight loss, 20 pounds (about 9 kilograms) or more, had a 26% lower risk compared to women whose weight remained stable.

Those with sustained weight loss of 4.4 to 10 pounds (2 to 4.5 kg) saw a 13% reduction in risk and those who lost 10 to 20 pounds (4.5 to 9 kg) had a 16% reduction in risk.

For a news article explaining the study, see here.