Women who lose weight — and keep it off — after age 50 have a lower risk of breast cancer than women whose weight remains stable, according to a study published this week in the Journal of the National Cancer Institute (JNCI).

The greater the weight loss, the greater the reduction in risk, although the study found that shedding even a small number of excess pounds — as few as 4.5 — lowered the chances of developing breast cancer.

Being overweight or obese is a well-established risk factor for developing breast cancer after menopause. It’s been less clear, however, whether losing excess weight could reverse that risk. This study — the largest on the topic to date — indicates it might.

Our results suggest that even a modest amount of sustained weight loss is associated with lower breast cancer risk for women over 50,” says Lauren Teras, the study’s lead author and an epidemiologist with the American Cancer Society, in a released statement. “These findings may be a strong motivator for the two-thirds of American women who are overweight to lose some of that weight. Even if you gain weight after age 50, it is not too late to lower your risk of breast cancer.”

We found that losing weight — and keeping it off — was associated with lower breast cancer risk for women aged 50 years and over,” Teras and her co-authors conclude.

“In other words, it is not too late to lower your risk of breast cancer if you have gained weight after age 50,” they add. “Prevention of the most common cancer worldwide may be a particularly motivating factor for the near epidemic numbers of overweight women.”