If you’re a woman, you should know that your risk of developing breast cancer increases as you age. But just know that there are things you can do to protect yourself. One study shows that losing weight after menopause may help reduce your risk of invasive breast cancer, and you don’t have to shed a lot of weight to do it. What’s more, you can take your time doing it.
Study author Dr. Rowan Chlebowski from City of Hope National Medical Center said of the 60,000-women study:
“The women [in the study] who lost 5% of body weight over just a 3-year period ended up having a 12% statistically significant reduction in breast cancer incidence.”
Obesity is a well-known risk factor for breast cancer in older women, Chlebowski said. But researchers didn’t know if losing weight could reduce that risk.
“It looks like once you get obese, there’s a lot of body signals that stimulate breast cancer growth and so the question is even a little moderate change in diet and moderate weight loss will reduce those signals.”
In the study, gaining more than 5% of body weight was not associated with breast cancer risk overall, but it was associated with a 54% higher risk of an especially serious and aggressive form of the disease, known as triple-negative breast cancer. 
Chlebowski and his colleagues tracked the outcomes of the post-menopausal women, with an average follow-up of 11 years. None of the women had a prior history of breast cancer and had normal mammogram results. The researchers weighed the women at the beginning of the study, and again 3 years later.
During follow-up, about 3,000 new cases of invasive breast cancer were diagnosed in the group.
Though the study was observational in nature, Chlebowski said the results “are also supported by randomized clinical trial evidence.”
 CBS News