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Study Finds Losing Weight After 50 May Lower Breast Cancer Risk

happy woman sitting on couch eating a bowl of fruit

Women who lose weight after age 50 and keep it off have a lower risk of breast cancer than women whose weight stays the same, according to a study from researchers at the American Cancer Society, the Harvard T.H. Chan School of Public Health, and others. Being overweight is a known risk for breast cancer after menopause, but this is the first large study to show that losing weight can reduce this risk. The findings did not include women using post-menopausal hormone therapy.

The study was published December 17, 2019 in the Journal of the National Cancer Institute.

More than 2 of out of 3 women in the US is overweight or obese. The findings show it’s never too late to benefit from losing weight, and that goes for women who’ve gained weight even after age 50. “Our results suggest that even a modest amount of sustained weight loss is associated with lower breast cancer risk for women over 50,” said Lauren Teras, PhD, lead author of the study.

The details

Researchers looked at 180,885 women from 10 studies in the Pooling Project of Prospective Studies of Diet and Cancer. They recorded the women’s weights 3 times over about 10 years: when they enrolled, about 5 years later, and about 5 years after that. Weight changes of 2 kilograms or less (about 4.4 lbs) were counted as stable.

They found the more weight women lost, the lower their risk of breast cancer. Losing even a small amount of weight lowered risk.

  • Women who lost 2 to 4.5 kg (about 4.4 to 10 lbs.) had a 13% lower risk than women with stable weight.
  • Women who lost 4.5 to 9 kg (10- 20 lbs.) had a 16% lower risk.
  • Women who lost 9 kg or more (20+ lbs.) had a 26% lower risk.
  • Women who lost 9 kg or more and gained some (but not all) of the weight back had a lower risk of breast cancer compared with those whose weight was stable.

Take control of your weight

Although the findings did not include women using post-menopausal hormone therapy and the results were seen more in women who were overweight or obese, Teras said getting to a healthy body weight has many health benefits and is a good goal for everyone.

Getting to a healthy weight and staying there is not easy for most people. Losing even a small amount of weight – for example, half a pound a week – is a good place to start.

Read our tips for making smart choices that can help you achieve a weight that’s right for you.

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.

Sustained weight loss and risk of breast cancer in women ≥50 years: a pooled analysis of prospective data. Published December 17, 2019 in Journal of the National Cancer Institute. First author Lauren R. Teras, PhD, American Cancer Society, Atlanta.