Mayo Clinic Study: Women on Hormone Therapy Lost 35% More Weight on Tirzepatide
Mayo Clinic Study: Women on Hormone Therapy Lost 35% More Weight on Tirzepatide
- Postmenopausal women on hormone therapy lost an average of 19.2% of body weight on tirzepatide over 12+ months.
- Women not on hormone therapy lost an average of 14.0% of body weight.
- That's a 35% greater relative weight loss in the hormone therapy group.
- More women in the hormone therapy group hit deeper weight-loss milestones (20%, 25%, and 30%+ of body weight).
- The study was observational, not randomized — so association can be shown but causation cannot be proven.
- Published in The Lancet Obstetrics, Gynaecology & Women's Health, January 2026. Lead author: Dr. Regina Castaneda, Mayo Clinic.
Earlier this year, a Mayo Clinic-led research team published a study in The Lancet Obstetrics, Gynaecology, & Women's Health that quietly validated something we've been seeing in our Centennial and Alamosa clinics for years.
The study followed 120 postmenopausal women with overweight or obesity who were prescribed tirzepatide — the GLP-1/GIP receptor agonist sold as Zepbound for weight management and Mounjaro for type 2 diabetes — for 12 months or longer. The researchers compared two groups: women who were also taking menopausal hormone therapy, and women who weren't.
The results were striking. Women on hormone therapy lost an average of 19.2% of their body weight. Women not on hormone therapy lost 14.0%. That's a 35% greater relative weight loss — and more women in the hormone therapy group hit the deeper weight-loss thresholds (20%, 25%, even 30% of body weight).
For the women we work with — many of whom are navigating perimenopause, menopause, weight gain that won't respond to what used to work, and the complicated emotional landscape of all of that at once — this study confirms what good clinical intuition has been pointing to. The hormonal context matters. You can't separate metabolism from the endocrine system, and you can't treat weight loss in postmenopausal women without taking the rest of the hormonal picture seriously.
Here's the honest clinical read on what this study found, what it didn't find, and what it should change about how women in their 40s, 50s, and beyond approach weight loss.
The Headline Numbers
The 35% number is what's gotten the most attention — and it's the one that translates most clearly into a real-world conversation. If you imagine a postmenopausal woman starting tirzepatide at 200 pounds, the difference is roughly 28 pounds lost without hormone therapy versus roughly 38 pounds with it. Over a year. Same medication.
But the deeper finding was that hormone therapy users were also more likely to hit the meaningful weight-loss milestones — the 20%, 25%, and 30%+ thresholds where cardiometabolic risk markers really start to improve. It wasn't just that they lost more weight on average; more of them crossed into the range where the health benefits compound.
Why This Might Be Happening
Women on hormone therapy may lose more weight on tirzepatide for three reasons: estrogen may enhance the appetite-suppressing effects of GLP-1 signaling, hormone therapy improves sleep quality by relieving hot flashes, and women on hormone therapy tend to be more engaged with their overall health. The mechanism is still being studied, but the leading hypotheses are well-grounded in existing research.
1. Estrogen and appetite regulation
Preclinical data — meaning animal studies and early lab work — suggests that estrogen may enhance the appetite-suppressing effects of GLP-1 signaling. The hormones aren't doing the same thing, but they may be amplifying each other when both are present. As estrogen levels drop in menopause, this potential synergy is lost. Adding hormone therapy back may restore part of that interaction.
2. Sleep, hot flashes, and quality of life
Up to 75% of postmenopausal women experience hot flashes and night sweats. These aren't just uncomfortable — they fragment sleep, drive cortisol up, increase insulin resistance, and make it dramatically harder to stick to lifestyle changes. Hormone therapy is the most effective treatment for these symptoms. When patients sleep better and feel better, they have more capacity to do the things that make any weight loss plan work.
3. Selection effects (the honest caveat)
The senior author of the study, Dr. Maria Daniela Hurtado Andrade, was direct about a limitation worth understanding: women who choose hormone therapy may already be more health-engaged. They may be exercising more, eating better, working more proactively on their care overall. That engagement could account for some — possibly much — of the difference observed.
This is why the study can show association but not causation. The researchers are clear: hormone therapy is associated with greater weight loss on tirzepatide in this population, but the study can't prove that hormone therapy is what's causing the extra loss.
The Honest Limitations
The Mayo Clinic study has four important limitations: it was observational rather than randomized, the sample size was small (120 women), it studied only tirzepatide, and the combination is not a separately FDA-approved indication. Before this gets oversold in headlines and TikTok videos — and it will — there are things this study is not:
- It is not a randomized controlled trial. Women weren't assigned to the hormone therapy group or the control group at random. They chose. That introduces real bias.
- It is not a large population study. 120 women is a meaningful sample but not a huge one. Results in smaller studies sometimes look bigger than they turn out to be in larger follow-up trials.
- It is not a study of all GLP-1s. The drug studied was tirzepatide specifically — the dual GLP-1/GIP agonist marketed as Zepbound and Mounjaro. The same effect may or may not extend to semaglutide (Wegovy, Ozempic) or to the newer triple-agonist drugs coming through approval pipelines.
- It does not change FDA approvals. Tirzepatide is approved for overweight, obesity, and type 2 diabetes. Hormone therapy is approved for menopausal symptoms. Using them together for the goal of enhanced weight loss isn't an officially approved combination indication — it's clinical decision-making in the context of a patient who happens to be a candidate for both.
The researchers themselves called for "prospective, randomised controlled trials" to confirm what they saw and clarify the mechanism. That's the right next step. In the meantime, the observational data is suggestive enough that it should be part of the conversation when postmenopausal women and their providers are deciding how to approach weight management.
What This Should Change About the Conversation
For decades, weight loss medicine and menopause medicine have been treated as separate conversations — often by separate specialists, often without much coordination. A patient might see a primary care provider for weight management, an OB-GYN for menopause symptoms, and never have anyone actually sit down and connect the two.
This study is one more piece of evidence that the separation is wrong. For postmenopausal women, the hormonal context is part of the metabolic context. Estrogen, progesterone, testosterone, and insulin sensitivity all interact. Treating weight as if it can be addressed without addressing the hormone shift, or treating menopause symptoms as if they don't influence metabolic health, leaves outcomes on the table.
What the data points toward — what we already do in practice at Defiance — is integrated care across four components:
- Comprehensive intake that maps the full hormone and metabolic picture before any treatment decisions are made
- Coordinated treatment where weight-management medications and hormone therapy are managed by the same clinical team, with the same chart, with full awareness of how they interact
- Honest expectation-setting that some women will see substantially better results with both pieces addressed simultaneously than with either alone
- Long-term follow-up because both weight management and hormone therapy are ongoing processes, not one-time prescriptions
How Defiance Approaches This Already
Defiance Health manages bioidentical hormone therapy (BHRT) and GLP-1 weight loss medications together — under the same clinical team, with the same chart, with full awareness of how they interact. At our hormone therapy and medical weight loss programs, this integrated model is the baseline, not an upsell.
The reason this matters operationally is that the Mayo Clinic finding only translates into real-world outcomes if a patient is actually treated by a team that's willing to address both. A weight loss clinic that doesn't do hormone therapy can't offer the combination. A menopause specialist who doesn't prescribe GLP-1s can't offer it either. Defiance Health has both lines of care under one roof — and our providers manage both for the same patients when clinically appropriate.
What that looks like in practice:
- A comprehensive metabolic and hormone panel as the foundation, available through our in-house lab testing
- An evaluation of menopause symptoms, current hormone status, and existing risk factors
- A discussion of options — including hormone therapy alone, GLP-1 alone, both together, or neither, depending on what the clinical picture supports
- Coordinated follow-up that tracks both weight outcomes and menopause-symptom outcomes over time
- Adjustments as the picture changes — because what works in year one may need to evolve in year three
Both our Centennial and Alamosa clinics offer this integrated approach. Telehealth is available for ongoing follow-up across Colorado.
For Patients on GLP-1s Alone — A Question Worth Asking
If you're a postmenopausal woman currently on tirzepatide (Zepbound or Mounjaro), or considering it, this study suggests a conversation worth having with your provider:
"Given my menopausal status, should we be considering hormone therapy as part of this plan?"
The right answer for any individual patient depends on factors that need to be evaluated clinically: your symptoms, your medical history, your personal and family history of breast cancer and cardiovascular disease, your age, how long you've been postmenopausal, and what your goals are. Hormone therapy isn't appropriate for every woman. But for many, it's a reasonable option that's been over-restricted for years based on outdated readings of older research — and this new data adds yet another consideration to the discussion.
The honest summary: For postmenopausal women considering or already on tirzepatide for weight loss, this Mayo Clinic study suggests menopausal hormone therapy may significantly enhance results. The data is associational rather than causal, but the magnitude (35% more weight loss) is large enough that it deserves real consideration. The conversation worth having with your provider: is hormone therapy a candidate for me — and if so, would it make sense alongside the weight loss treatment I'm already pursuing?
Why We're Watching This Space
The Mayo Clinic study is one piece of a much larger shift happening in 2026. GLP-1 medications are being increasingly understood as "multi-system metabolic modulators" rather than simple weight-loss drugs. They're being studied for cardiovascular protection, kidney function, liver health, even brain health and Alzheimer's risk. Hormone therapy is being re-evaluated after decades of restriction following the misread Women's Health Initiative results. Both fields are evolving fast — and the intersections between them are where some of the most interesting clinical findings of the next few years are likely to emerge.
Our job, as the clinicians treating individual patients, is to keep up with the data, integrate what's well-supported into practice, and be honest with patients about what we know and what we don't. This study is one more piece of the picture for postmenopausal women trying to manage weight in a hormonal landscape that's been working against them.
Considering BHRT, GLP-1s, or both?
Schedule a consultation at our Centennial or Alamosa clinic to discuss whether integrated hormone and metabolic care is the right approach for you.
Book a ConsultationThis blog post is for educational purposes only and does not constitute medical advice. The Mayo Clinic study referenced is observational and cannot prove causation; results may not generalize to all postmenopausal women or all GLP-1 medications. Tirzepatide is FDA-approved for overweight, obesity, and type 2 diabetes; the combination with hormone therapy for enhanced weight loss is not a separately FDA-approved indication. Hormone therapy is not appropriate for all women and carries risks that should be evaluated with a qualified clinician based on individual history and circumstances. All treatment decisions should be made in consultation with a licensed medical provider. Individual results vary.