A new study out of Mayo Clinic is making the rounds this week, and if you are a woman in menopause who has tried a GLP-1 medication with mixed results, it is worth understanding, carefully. Researchers looked at 120 postmenopausal women taking tirzepatide for a year or more and found that those who were also on menopausal hormone therapy lost roughly 35 percent more weight than women on tirzepatide alone. That is a striking number, and it is already showing up in health news everywhere. But here is the catch the headlines tend to skip: this was an observational study, not a randomized trial, and the lead researchers themselves say plainly that they cannot conclude hormone therapy caused the extra weight loss. It is a real and interesting signal, not yet proof. Below, I will walk through what the study actually did, why the distinction matters, and how this fits into medically supervised care.
What did the study actually find?
Researchers at Mayo Clinic, led by Dr. Regina Castaneda with senior author Dr. Maria Daniela Hurtado Andrade, published a retrospective cohort study in The Lancet Obstetrics, Gynaecology, & Women’s Health looking at 120 postmenopausal women with overweight or obesity who had been on tirzepatide (brand names Zepbound/Mounjaro) for 12 months or longer (Mayo Clinic News Network coverage). Women who were also using menopausal hormone therapy (MHT) during that period lost approximately 35 percent more total body weight than women taking tirzepatide by itself.
Dr. Castaneda, the study’s lead author, called the size of the difference notable: “The magnitude of this difference warrants future studies that could help clarify how GLP-1-based obesity medications and menopausal hormone therapy may interact.” Dr. Hurtado Andrade was direct about the study’s limits and next steps: “Because this was not a randomized trial, we cannot say hormone therapy caused additional weight loss... We plan to test these observations in a randomized clinical trial.”
Why “observational” matters so much here
This is the single most important thing to understand about this study, so it is worth spelling out. In an observational (retrospective cohort) study, researchers look backward at outcomes for two groups of people who made their own choices about treatment. Nobody was randomly assigned to hormone therapy or not. That means the two groups could differ in ways that have nothing to do with the hormones themselves.
The Mayo team named this directly: women who chose to start hormone therapy may also have been more likely to be engaged with their overall health, sleeping better, exercising more consistently, or working with a provider who was generally more attentive to their metabolic health. Any of those factors alone could explain part of the weight-loss difference. This is exactly why the researchers are planning a randomized controlled trial, the only study design that can actually test cause and effect here.
None of that makes the finding unimportant. It is a strong enough signal that a serious academic medical center is now designing a trial to test it directly. It just means the honest answer today is “promising and worth watching,” not “proven.”
Why might hormone therapy and GLP-1s work well together, biologically?
There are plausible mechanisms, even though they have not been confirmed in this population:
- Estrogen affects fat distribution and insulin sensitivity. Declining estrogen during menopause is associated with a shift toward central (visceral) fat storage and reduced insulin sensitivity, both of which can work against weight-loss efforts (Fenton, 2021, Menopause and body composition).
- Sleep and mood interact with appetite regulation. Hormone therapy often improves menopause-related sleep disruption and vasomotor symptoms (hot flashes, night sweats), which independently affects hunger hormones and adherence to a weight-loss plan.
- Both therapies touch metabolic pathways. GLP-1 medications act on appetite and glucose regulation; estrogen has known effects on lipid metabolism and energy expenditure. It is biologically plausible they would have additive or synergistic effects, but plausible is not the same as proven.
Is hormone therapy right for you? That is a different, and more important, question
Menopausal hormone therapy is its own significant medical decision with its own risk-benefit profile that has nothing to do with weight loss. It is prescribed primarily for symptom relief (hot flashes, night sweats, vaginal atrophy, sleep and mood symptoms) and bone health, and it carries considerations around personal and family history, timing since menopause onset, and cardiovascular and cancer risk factors that a qualified provider needs to screen for individually. Nobody should start or stop hormone therapy based on a single observational study about weight loss. That conversation belongs with a provider who can review your full history.
What this means for medically supervised GLP-1 care
Here is how I would frame this for a client asking about it in clinic. If you are a menopausal woman already considering hormone therapy for symptom relief, hot flashes, sleep, mood, and you are also using or considering a GLP-1 medication for weight management, this study is a reasonable thing to bring up with your provider as one more data point in that conversation. It is not, by itself, a reason to start hormone therapy purely to boost weight loss on a GLP-1.
At Vitality Dartmouth, this is exactly the kind of nuance we walk through with clients:
- Full picture first. Labs and biomarkers before any medication conversation, not just for weight loss, but for the hormone-therapy conversation too, if that is relevant to you.
- Genomic context. Our genomic testing looks at markers relevant to metabolism, inflammation, and hormone-related pathways, useful context for individualizing a plan.
- Coordinated, not siloed, care. If hormone therapy is appropriate for your symptoms, we make sure that decision is made on its own merits, not retrofitted as a weight-loss hack, while your GLP-1 program (including options like retatrutide, offered through our clinic for appropriate, screened candidates, and note it is an investigational medication not yet FDA-approved) is titrated and monitored separately.
- Muscle-first programming. Protein targets and resistance training through our coaching programs, regardless of which medications are or are not part of your plan.
- Realistic expectations. We will not tell you a 35 percent weight-loss boost is guaranteed because two things were combined in someone else’s retrospective chart review. We will tell you what the current evidence actually supports.
Frequently asked questions
Should I ask my doctor to add hormone therapy just to lose more weight on my GLP-1?
Not based on this study alone. Hormone therapy has its own indications and risks that should be evaluated on their own terms. If you have menopause symptoms that hormone therapy could help with, this research is a reasonable thing to raise in that conversation, not a stand-alone reason to start.
Does this mean tirzepatide doesn't work as well without hormone therapy?
No. Tirzepatide has strong randomized trial evidence for weight loss on its own. This study looked at whether adding hormone therapy provided additional benefit in women already using tirzepatide. It did not question tirzepatide's baseline effectiveness.
When will we know if hormone therapy actually causes extra weight loss?
The Mayo Clinic researchers have stated they plan to test this in a randomized controlled trial, which is the only design that can establish cause and effect. Until then, this remains an observed association.
Do you see clients near me?
Yes. Vitality Dartmouth is based in Dartmouth, MA and works with clients across the SouthCoast, including New Bedford, Westport, Fairhaven, and Fall River, for medically supervised weight loss, menopause care, and genomic-guided coaching.
The bottom line
A new Mayo Clinic study found that postmenopausal women combining hormone therapy with tirzepatide lost about 35 percent more weight than those on tirzepatide alone, a genuinely interesting finding from a well-regarded research team. But it is observational data, the researchers themselves say it cannot prove cause and effect, and a randomized trial is still needed. The right takeaway is not “start hormone therapy for weight loss.” It is “if hormone therapy is already on your radar for menopause symptoms, this is one more thing worth discussing with a provider who can look at your whole picture.”
If you are navigating menopause, weight changes, and want a coordinated, medically supervised plan built around your actual labs and history rather than headlines, that is exactly what a consult is for.
This article is for educational purposes only and is not medical advice. It summarizes an observational study; the authors themselves caution that it cannot establish that hormone therapy causes additional weight loss. Hormone therapy and GLP-1/retatrutide-class medications are prescription treatments with individual risks and contraindications; retatrutide is an investigational medication that has not been approved by the FDA. Discuss any treatment decision with a licensed healthcare provider. Individual results vary.