Postmenopausal Women Lost 35% More Weight on Tirzepatide When They Were Also on Hormone Therapy

For postmenopausal women using GLP-1 medications, this is the most directly relevant study to come out of a major research center in some time. The question it addresses is whether hormone therapy changes how well tirzepatide works. The answer from this data is: possibly, and meaningfully so.

What the study looked at

Researchers at Mayo Clinic Jacksonville reviewed records from 120 postmenopausal women with overweight or obesity who had been taking tirzepatide for weight management for at least 12 months. Forty of those women were also using menopausal hormone therapy. The other 80 were on tirzepatide alone. The team compared weight loss outcomes between the two groups, controlling for baseline characteristics.

The study was led by Regina Castaneda, M.D., a postdoctoral research fellow at Mayo Clinic, and was published in January 2026 in The Lancet Obstetrics, Gynaecology, & Women's Health. Senior author was Maria Daniela Hurtado Andrade, M.D., Ph.D., an endocrinologist at Mayo Clinic.

The numbers

Women using both tirzepatide and hormone therapy lost an average of 17% of their body weight over the study period. Women on tirzepatide alone lost an average of 14%. That 3-percentage-point gap represents roughly 35% more weight lost relative to the tirzepatide-only group.

The difference was sharper at the high end of outcomes. Among women on both therapies, 45% achieved a total body weight loss of 20% or more. In the tirzepatide-only group, that figure was 18%, less than half the rate.

What might explain it, and what might not

"In this observational study, women who used menopausal hormone therapy lost about 35% more weight than women taking tirzepatide alone. Because this was not a randomized trial, we cannot say hormone therapy caused additional weight loss," Dr. Hurtado Andrade noted in the Mayo Clinic press release accompanying the study.

The researchers acknowledged the obvious confounders. Women who use hormone therapy may already be more engaged with their health, sleeping better because their hot flashes are controlled, or more consistent with diet and activity changes, all of which could drive better weight loss outcomes independent of any pharmacological interaction between the two drugs.

That said, they were not working purely from speculation. Preclinical evidence does suggest a plausible biological mechanism: estrogen appears to enhance the appetite-suppressing effects of GLP-1 receptor signaling. If that interaction exists in humans at meaningful levels, hormone therapy would not just treat menopause symptoms; it would also amplify what the GLP-1 is doing. That is the hypothesis the planned randomized trial is designed to test.

Why it matters for this audience

Tirzepatide is a dual GIP/GLP-1 receptor agonist, meaning it activates two pathways instead of one, which is part of why it tends to produce stronger weight loss results than semaglutide in head-to-head comparisons. What this study adds is the suggestion that the hormonal environment a woman is in might modulate that effect further.

Menopause does not just cause symptoms. The estrogen decline that defines it is also associated with metabolic changes, including increased central adiposity, shifting lipid profiles, and elevated cardiovascular risk, that make weight management both harder and more important at exactly the time many women are considering GLP-1 therapy for the first time. If hormone therapy and GLP-1s have a synergistic effect in this population, that would be a meaningful clinical finding for a very large group of women.

Previous research had found a similar pattern with semaglutide: postmenopausal women on hormone therapy also showed better weight loss outcomes in that data. The Mayo Clinic study is the first to look at tirzepatide specifically.

What comes next

Dr. Castaneda and Dr. Hurtado Andrade say the next step is a randomized clinical trial that can directly test whether the combination causes better outcomes, and whether the benefits extend beyond weight loss to cardiovascular and metabolic measures. That trial has not yet been announced publicly.

In the meantime, the study suggests that postmenopausal women already on hormone therapy who are starting or already using tirzepatide may have an advantage worth knowing about. For women whose menopause symptoms are uncontrolled, addressing those symptoms might improve their GLP-1 outcomes in ways that had not been formally recognized until now.