Exercise is often praised for building strength and improving heart health, but new research from the University of British Columbia’s Okanagan campus suggests it could also play an important role in helping breast cancer survivors manage their weight.
Dr. Sarah Purcell, a researcher with UBC’s Southern Medical Program and the Center for Chronic Disease Prevention and Management, recently published a study looking at how exercise affects women undergoing estrogen-blocking therapy.
This treatment, a standard part of long-term breast cancer care, can last five to ten years and is known to lower hormone levels.
“Breast cancer survivors generally have good survival rates,” explains Dr. Purcell. “But many face an increased risk of weight gain, which can lead to obesity, heart disease, diabetes, and even cancer recurrence.
Understanding why this happens is an important part of improving their long-term health.”
Weight gain after breast cancer treatment is a common but poorly understood problem.
Doctors suspect it may be linked to the reduced estrogen levels that result from endocrine therapy.
This drop in hormones changes how the body functions, but the exact mechanisms behind treatment-related weight gain remain unclear.
To explore this, Dr. Purcell’s team compared data from two randomized trials.
They studied women with obesity or high body weight, including breast cancer survivors on estrogen-blocking therapy, all of whom were premenopausal before their cancer diagnosis. The focus was on how exercise influenced appetite and related hormones.
The results were surprising. After exercise, the breast cancer survivors had higher levels of Peptide YY (PYY), a hormone that naturally suppresses appetite, compared to women without a history of cancer.
This finding was the opposite of what the researchers expected. Estrogen-blocking therapies are typically associated with weight gain, yet here was evidence that exercise triggered a stronger appetite-reducing response in survivors.
“What we found was that exercise seemed to boost the appetite-suppressing effect in women on estrogen therapy,” says Dr. Purcell.
“Although the survivors didn’t report feeling less hungry, their hormone levels told a different story—they showed stronger appetite control and ate less relative to their body size following exercise.”
This discovery suggests that physical activity may help breast cancer survivors manage their weight in ways that go beyond simply burning calories. By improving the body’s natural appetite-control systems, exercise may counter some of the effects of long-term hormone therapy and support healthier body composition.
While more research is needed, the study offers a hopeful message: exercise is not only safe but may be especially valuable for women recovering from breast cancer. For survivors concerned about weight changes during treatment, physical activity could be a powerful tool for staying healthy, reducing risks of other diseases, and potentially lowering the chance of cancer returning.
“This shows a novel interaction between exercise and estrogen suppression,” Dr. Purcell concludes.
“It highlights just how important exercise can be—not just for strength or endurance, but for managing appetite and overall health in breast cancer survivors.”
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.
