New research from Mayo Clinic suggests postmenopausal women who add menopausal hormone therapy to tirzepatide treatment may see larger weight losses than those taking the drug alone, though the study was observational and not definitive. The analysis compared outcomes for 120 women on tirzepatide for at least a year, with 40 also using hormone therapy and 80 not, and found a notable difference in average weight change. Researchers and outside experts stress the need for randomized trials to untangle whether the hormone therapy itself boosts weight loss or if other factors explain the gap.
Researchers looked at 120 postmenopausal women who were overweight or obese and had been on tirzepatide for a minimum of 12 months. Forty of those women were also using menopausal hormone therapy while 80 were not, giving the team two groups to compare within routine clinical care. Tirzepatide is a GLP-1–based medication that helps control appetite and blood sugar, while hormone therapy is commonly prescribed to ease menopausal symptoms like hot flashes and night sweats.
On average, women who combined hormone therapy with tirzepatide lost 19.2% of their body weight, compared with 14.0% in the group taking tirzepatide alone. That translates to roughly 35% greater relative weight loss in the hormone therapy group and a higher share of women hitting clinically meaningful weight-loss milestones. Those numbers are striking, but the study design prevents drawing firm conclusions about cause and effect.
“This study provides important insights for developing more effective and personalized strategies for managing cardiometabolic risk in postmenopausal women,” Dr. Regina Castaneda, the study’s first author, said in a statement. The team highlighted the potential clinical importance of tailoring approaches to obesity in the context of menopause, where hormonal shifts change fat distribution and metabolic risk. Still, observational signals like this need cautious interpretation before changing practice.
“Because this was not a randomized trial, we cannot say hormone therapy caused additional weight loss,” said Dr. Maria Daniela Hurtado Andrade, an endocrinologist at Mayo Clinic and senior author of the study. Observational comparisons can be influenced by underlying differences between groups, such as overall health, lifestyle habits, or access to care. That makes it hard to tell whether estrogen itself boosted the drug’s effect or if other factors explain the extra weight loss.
Outside clinicians pointed out similar concerns about confounding and selection bias. “As with all observational studies, we need to interpret this study with a grain of salt,” Dr. Gillian Goddard, a board-certified endocrinologist, told reporters. She noted that women prescribed estrogen might differ in meaningful ways, including being more proactive about diet and exercise or having fewer comorbidities that limit activity.
One practical idea is that symptom relief from hormone therapy could indirectly support weight management by improving sleep, mood, and energy, making it easier to stick with healthy habits. The study authors mentioned that better sleep and overall well-being could have helped the hormone therapy group maintain diet and exercise routines. Those behavioral pathways could explain part of the observed advantage without requiring a direct drug interaction.
There is also a plausible biological angle to explore: preclinical work suggests estrogen might amplify the appetite-suppressing effects of GLP-1–based medications like tirzepatide. “The other possibility is that estrogen interacts with tirzepatide in some way that makes it more potent,” she said. If true, that interaction would be important to confirm, but it remains a hypothesis until randomized clinical trials test it directly.
Safety matters too: combining hormone therapy and GLP-1 drugs appears safe for many women, yet hormone therapy is not appropriate for everyone. Patients with histories of certain cancers, blood clots, or other specific health risks are usually advised against systemic hormone therapy. Any decision about adding menopausal hormone treatment should be individualized and made with a clinician who knows the patient’s full medical picture.
To move beyond the current limits of observational evidence, researchers say future randomized trials will be needed to confirm whether combining hormone therapy with tirzepatide truly boosts weight loss and whether it improves cardiometabolic outcomes. If randomized data back these findings, clinicians could gain a new, evidence-based option for addressing weight and metabolic risk in postmenopausal women. Until then, the observation is interesting and potentially promising, but not practice-changing on its own.
