Hormone Therapy May Enhance Weight Loss Effects of Obesity Drugs After Menopause, Study Finds

Postmenopausal women struggling with weight gain may find a promising new approach by combining hormone therapy with popular weight loss medications, according to new research from the Mayo Clinic.

The study, published in The Lancet Obstetrics, Gynaecology, & Women’s Health in February, found that women who used menopausal hormone therapy alongside tirzepatide—an FDA-approved GLP-1-based drug for obesity—lost approximately 35% more weight than those taking the medication alone.

“This study provides important insights for developing more effective and personalized strategies for managing cardiometabolic risk in postmenopausal women,” said Dr. Regina Castaneda, the study’s lead author.

Researchers analyzed data from 120 postmenopausal women with overweight or obesity who had been taking tirzepatide for at least 12 months. Among them, 40 were also using hormone therapy while 80 were not. The results showed women in the hormone therapy group lost an average of 19.2% of their body weight, compared to 14.0% in the non-hormone group.

The findings address a critical health concern for women entering menopause, a life stage when hormonal changes typically increase the risk of weight gain, obesity, cardiovascular disease, and type 2 diabetes.

Hormone therapy, which typically includes estrogen, is already widely prescribed to manage common menopausal symptoms such as hot flashes and night sweats. Tirzepatide, sold under brand names like Mounjaro and Zepbound, works by regulating appetite and blood sugar levels.

However, experts caution that the study’s observational design has limitations. “Because this was not a randomized trial, we cannot say hormone therapy caused additional weight loss,” emphasized Dr. Maria Daniela Hurtado Andrade, the study’s senior author and an endocrinologist at Mayo Clinic.

Outside medical experts agree that the results should be interpreted carefully. Dr. Gillian Goddard, a board-certified endocrinologist and adjunct assistant professor at NYU Grossman School of Medicine, noted that the study shows a correlation but doesn’t prove causation.

“As with all observational studies, we need to interpret this study with a grain of salt,” Goddard said. “There may be important differences between the two groups. For one thing, the group taking estrogen may be healthier than the groups that didn’t take estrogen.”

Researchers have proposed several theories to explain the enhanced weight loss. One possibility is that symptom relief from hormone therapy may have improved sleep quality and overall well-being, making it easier for women to maintain healthy diet and exercise routines alongside their medication.

The researchers also pointed to potential biological mechanisms. Preclinical data suggests estrogen might enhance the appetite-suppressing effects of GLP-1-based medications like tirzepatide, though this interaction requires further investigation.

“The other possibility is that estrogen interacts with tirzepatide in some way that makes it more potent,” Goddard said, adding, “We will need randomized studies to get a better handle on that.”

Regarding safety, experts indicate that combining these treatments appears safe for most women. However, hormone therapy isn’t suitable for all patients, particularly those with a history of certain cancers, blood clots, or other underlying health conditions, according to the Mayo Clinic.

The potential impact of this research extends beyond weight management. Postmenopausal women face elevated risks for various cardiometabolic conditions, and more effective weight loss strategies could help mitigate these dangers.

“If confirmed, this work could speed the development and adoption of new, evidence-based strategies to reduce this risk for millions of postmenopausal women navigating this life stage,” said Hurtado Andrade.

The research team plans to conduct randomized controlled trials to validate these preliminary findings and explore whether the combination therapy also improves broader health outcomes such as cardiovascular and metabolic markers. Such trials would provide more definitive evidence about whether hormone therapy directly enhances the effectiveness of weight loss medications in postmenopausal women.

With over 1 million American women entering menopause each year and obesity affecting nearly 42% of U.S. adults, the potential clinical implications of this research are substantial, offering a possible new avenue for addressing both menopausal symptoms and weight management challenges simultaneously.