Exercise is known for building strength and improving heart health.
But new research from UBC Okanagan shows it may also help breast cancer survivors control their weight through hormone changes—something that could reduce future health risks.
Dr. Sarah Purcell, who works with UBC’s Southern Medical Program and the Centre for Chronic Disease Prevention and Management, studied how exercise affects women who have survived breast cancer and are receiving estrogen-blocking therapy. This therapy is common and usually lasts for five to ten years after treatment.
While breast cancer survivors often live long lives, many gain weight after treatment. This weight gain can lead to obesity, which increases the risk of heart disease, diabetes, and even cancer returning. Doctors have long wondered why this weight gain happens, especially since many survivors are trying to stay healthy.
Dr. Purcell believes the problem might come from low estrogen levels caused by the long-term therapy. “We don’t fully understand why some breast cancer survivors gain weight,” she said. “But estrogen loss may play a role.”
Her new study, published in the journal Nutrition and Cancer, looked at two groups: women who survived breast cancer and were on estrogen-blocking therapy, and adults who were obese or had high body weight. All the women had been premenopausal before their cancer diagnosis and were now receiving hormone treatment.
Exercise is already recommended for breast cancer survivors. Activities like walking, running, and lifting weights can improve heart health, muscle strength, and body composition. But Dr. Purcell’s research shows exercise may also help these women manage their appetite.
In the study, women who were taking estrogen-blockers had higher levels of a hormone called Peptide YY (PYY) after exercising. This hormone helps reduce hunger. Surprisingly, these women showed stronger appetite-reducing responses than people without cancer.
“We didn’t expect this result,” said Dr. Purcell. “We thought the therapy would make it harder to control appetite. But we saw the opposite—exercise increased PYY, which helps reduce hunger.”
Even though the women didn’t say they felt less hungry, their hormone levels and how much they ate showed they were eating less compared to their body size after exercising. This suggests that exercise may activate the body’s natural systems that help control appetite, especially in those on hormone therapy.
Dr. Purcell says this finding could help doctors recommend better ways to manage weight in breast cancer survivors. Exercise, she says, is more powerful than we thought—not just for fitness, but also for helping survivors avoid long-term health problems linked to weight gain.
“Exercise might be working in ways we never expected,” she said. “And it could make a big difference for women going through this tough stage of recovery.”
If you care about cancer risk, please read studies that exercise may stop cancer in its tracks, and vitamin D can cut cancer death risk.
For more health information, please see recent studies that yogurt and high-fiber diet may cut lung cancer risk, and results showing that new cancer treatment may reawaken the immune system.
The study is published in Nutrition and Cancer.
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