For women over 50, losing as few as four and a half pounds and keeping the weight off is associated with a lower risk of breast cancer, according to recent study findings, NBC News reports.

The findings don’t prove a causal relationship between slimming down and avoiding the second most common—and second deadliest—cancer among women. Nevertheless, the research suggests that women may have more power to reduce their risk than they realize.

Research has long since established that obesity itself raises postmenopausal women’s risk of breast cancer. About two thirds of women in the United States are overweight or obese.

According to the American Cancer Society, an estimated 268,600 new cases of invasive breast cancer and nearly 63,000 new cases of early-stage breast cancer were diagnosed in 2019.

Lauren Teras, PhD, the scientific director for epidemiology research at the American Cancer Society, led a new analysis of data from 10 studies involving nearly 181,000 women older than 50 who were followed for a decade. During that time, the women were diagnosed with nearly 7,000 cases of invasive breast cancer.

The findings were published in the JNCI: Journal of the National Cancer Institute.

Looking at weight measurements that were taken at the beginning, middle and end of the study’s follow-up period, the investigators found that compared with women who did not lose weight, women who lost between 4.5 and 10 pounds and sustained the weight loss had an 18% lower risk of breast cancer, while those who sustained 10 to 20 pounds of weight loss had a 32% lower risk.

If women lost at least 20 pounds but gained back some but not all of it, they still had a reduced risk of breast cancer compared with those who didn’t lose weight.

For women who took hormone therapy, weight loss was not associated with a reduced breast cancer risk. Hormone therapy may increase breast cancer risk, studies suggest. 

The new research has broad implications for American women. Obesity has been found to increase the odds of developing breast cancer as well as breast cancer recurrence, while weight loss surgery has recently been found to reduce the risk of many cancers, including breast cancer. Excess body fat drives up levels of estrogen and other hormones and stirs chronic low-level inflammation, all of which may fuel the development of breast cancer.

To read the NBC News article, click here.

To read the study abstract, click here.


To learn more, see the Cancer Health article, “A Low-Fat, Plant-Based Diet Cuts the Risk of Dying of Breast Cancer.”