Some women shrug off their post-menopausal weight gain as inevitable but a study from Harvard Medical School and School of Public Health adds to the growing evidence that women who avoid weight gain, including after menopause, have a lower risk of breast cancer. In fact, according to the study, women can substantially decrease their risk by losing weight after menopause.
The study data was taken from the ongoing Nurses’ Health Study and researchers assessed weight changes in more than 80,000 women who were followed for up to 26 years. The researchers found that women who had gained a hefty 55 pounds (25 kg) in the years since age 18 had the sharpest increased risk — 45% — compared with women whose weight remained about the same. Surprisingly, the study determined that a weight gain of 4.4 pounds (2 kg) or more since the age of 18 was linked to 15% of breast cancers. Conversely, women who lost 22 pounds after menopause lowered risk. The lowest risk of all was enjoyed by women who lost weight after menopause and who had never been on hormone replacement therapy (HRT).
A. Heather Eliassen, ScD, an associate epidemiologist and instructor of medicine at Harvard Medical School, was the study’s lead author. She explained that previous studies have established the association of breast cancer risk and higher levels of sex steroid hormones (estrogen and androgens) and their metabolites. The reason: Adipose (fat) tissue produces estrogens including in women after menopause. The message of this study, she says, is for women to understand that any long-lasting weight gain, including small amounts — whether before or after menopause — increases estrogens, which in turn increases breast cancer risk after menopause.
Dr. Eliassen adds that there was nothing magical about losing weight in the post-menopause years — the study simply showed that it is never too late. She reminds pre-menopausal women that it is harder to lose later, so it makes sense to achieve and maintain a normal weight now.
