Does HRT Cause Weight Gain? What 28 Trials Found

Q: Why am I gaining weight in perimenopause if it is not the hormones?

Midlife women gain about half a kilogram a year with age. During the transition, the rate of fat gain doubles while lean mass starts to fall, which changes shape more than weight.

Body · The Reading Room · 8 min read · What 28 randomized trials found about hormone therapy and the scale, and why the number moved anyway

Based on the published research of Susan R. Davis, AO, MBBS, PhD, FRACP, Vice-Chancellor’s Distinguished Professor and Head of the Women’s Health Research Program, Monash University, and past president of the International Menopause Society. Monash research profile · Google Scholar · the review on PubMed

The patch went on in March. The scale moved by June. Those two facts are next to each other, which is not the same as one causing the other.

It took you two years to book the appointment and another three months to actually start. The night sweats eased within weeks. You slept through, twice in one week, for the first time since the reorganization.

And then the jeans. Four pounds, give or take, and a waistband that has opinions.

So at eleven at night you type the question you have been half-asking since the first week: does HRT cause weight gain? Because if it does, you are not sure the sleep is worth it, and you are already rehearsing how to tell your doctor you want to stop.

Before you do, here is what the trials actually found. Informational, not medical advice, and worth taking to your prescriber rather than instead of one. This is a reading of published research. We are not clinicians; the findings belong to the researchers named below, and the plain-English version is ours.

The short answer: on the best evidence available, no. A Cochrane review of 28 randomized trials in 28,559 women found no evidence that estrogen alone or estrogen with a progestogen changed body weight beyond what women usually gain at that age.¹ The weight that arrives in midlife is driven mainly by aging, at roughly half a kilogram a year, while the menopause transition changes where fat is stored.² If anything, most studies of estrogen therapy point toward less overall fat mass, not more.²

The skim version

The Cochrane review pooled 28 randomized trials and 28,559 women. No evidence that hormone therapy affects weight or BMI beyond the usual midlife gain.¹
Midlife women gain about 0.5 kg a year with age. In SWAN, the average gain over three years was 2.1 kg.²
The International Menopause Society’s review found weight gain “does not appear to be affected by the hormonal changes of the menopause.” The distribution of fat does change.²
In 1,246 SWAN women, the rate of fat gain doubled at the start of the transition while lean mass began to fall, and it kept going until about two years after the final period.³
Because fat went up while muscle went down, the scale barely showed it. The change was in composition, not the number.³
The early side effects of HRT, such as breast tenderness or nausea, usually settle within a few weeks.⁴

In this article: What the trials found · So why did the scale move? · Sorting out the causes · Before you stop · The one move · FAQ

Does HRT cause weight gain? What the trials found

This is one of the few questions in menopause care where the evidence is unusually clean, because it was tested the right way.

Observational studies, where you simply compare women who chose HRT with women who did not, are easy to fool. The women who choose it may differ in a dozen other ways. Randomized trials remove that problem: a coin decides who gets the hormone and who gets the placebo, and then you weigh everyone.

The Cochrane review, led by Eugene Kongnyuy with Robert Norman and colleagues, gathered 28 of those trials, involving 28,559 women. Its conclusion was plain: there was no evidence of an effect of estrogen alone, or estrogen combined with a progestogen, on body weight or on the BMI increase normally experienced at the time of menopause.¹ The women on hormones and the women on placebo gained, on average, the same.

That also cuts the other way, and it is worth being honest about. The same review found HRT does not prevent the usual midlife weight gain either.¹ It is not a weight treatment. It is simply not the cause.

So why did the scale move after I started estradiol?

Three reasons, and none of them is the patch.

The first is time. Susan Davis and her colleagues on the International Menopause Society’s writing group put the baseline at a steady gain of about half a kilogram a year in midlife women, and noted that the SWAN cohort gained a mean of 2.1 kg over three years.² Pick any three months in your late forties and a pound or two is roughly what the calendar delivers. The patch just happened to be the new thing in those three months, so it got the blame.

The second is where fat goes. The IMS review is careful here. Weight gain itself does not appear to be driven by the hormonal changes of menopause, but those changes are associated with more total body fat and, in particular, more abdominal fat.² So the waistband changes before, or more than, the scale does.

The third is the part nobody sees on a bathroom scale. Gail Greendale’s team at UCLA measured body composition in 1,246 SWAN women with scans rather than scales. At the start of the transition, the rate of fat gain doubled, in the authors’ words, while lean mass switched from rising slightly to falling by about 0.2 percent a year. That continued until roughly two years after the final period, then leveled off.³

Here is the detail that matters most for you. Because fat was going up while muscle was going down, the authors found no discernible change in the rate of weight gain at the start of the transition.³ The body was changing shape while the number stayed politely quiet. Many women only notice it through clothes, which is exactly the moment many of them also start HRT.

What the research found

The review. Davis, Castelo-Branco, Chedraui, Lumsden, Nappi, Shah and Villaseca, for the International Menopause Society, “Understanding weight gain at menopause”, Climacteric, 2012.

The finding. Midlife weight gain tracks aging, at about 0.5 kg a year, and does not appear to be affected by the hormonal changes of menopause. Those changes are associated with more total and abdominal fat. Studies mostly indicate a reduction in overall fat mass with estrogen and estrogen-progestin therapy, along with improved insulin sensitivity and a lower rate of type 2 diabetes.² The Cochrane review of 28 trials found no effect of hormone therapy on weight or BMI.¹

The limitation: these are averages across many women and many hormone regimens, and the Cochrane trials varied in dose, type and length. Some individuals do report changes on a particular product, and an average cannot rule that out for you. What the evidence does rule out is the idea that weight gain is an expected, built-in effect of hormone therapy.

If the waistband is one more thing you have been quietly managing on top of everything else, it is worth ten minutes to see the whole picture in one place before deciding what to change. Start here.

The source for this piece

Susan R. Davis, AO, MBBS, PhD, FRACP

Vice-Chancellor’s Distinguished Professor at Monash University and Head of its Women’s Health Research Program, and Consultant Endocrinologist and Head of the Women’s Endocrine Clinic at the Alfred Hospital, Melbourne. Her research covers sex hormones in women across the lifespan, from basic science to clinical trials. She is a past president of both the Australasian and International Menopause Societies, a founding member of Jean Hailes for Women’s Health, and was appointed an Officer of the Order of Australia for distinguished service to women’s health.

What we read: Davis, S. R., et al., “Understanding weight gain at menopause”, Climacteric, 2012.²

Where to follow her work: Monash research profile · her writing for Monash Lens · Google Scholar · ResearchGate · International Menopause Society · LinkedIn

Does estradiol cause weight gain, or is it something else? Sorting out the causes

If you are trying to work out what is actually changing, this is the side-by-side view.

What might be behind it	What the evidence says	What it looks like
Hormone therapy itself	No effect on weight or BMI across 28 randomized trials¹	Timing coincides with starting, which is why it gets blamed
Age	About 0.5 kg a year in midlife women²	Slow, steady, and easy to pin on whatever else changed
The transition	Fat gain rate doubles, lean mass starts to fall³	Clothes fit differently before the scale shows much
Where fat is stored	More abdominal fat with the hormonal changes²	Waist measurement rises; the number on the scale may not
Early side effects	Breast tenderness, nausea and similar effects usually settle in weeks⁴	Feeling fuller or tender in the first weeks, then easing

Read down the middle column. Only one row is about the hormone, and it is the one with the most evidence behind it saying no.

Who else has measured this

Gail A. Greendale, MD, Emeritus Professor in the Division of Geriatrics at UCLA, led the SWAN analysis that measured body composition across the transition. In 1,246 women, fat gain doubled and lean mass began to decline at the start of the transition, continuing until about two years after the final period, while the rate of weight gain itself showed no discernible change.³
UCLA Geriatrics research faculty · Doximity profile · the 2019 study in JCI Insight · free full text via PubMed Central

Robert J. Norman, AO, Emeritus Professor at the University of Adelaide and a reproductive medicine researcher, is a senior author of the Cochrane review that pooled 28 randomized trials and 28,559 women and found no effect of hormone therapy on body weight.¹
Wikipedia · his writing for The Conversation · the Cochrane summary · LinkedIn

The NHS gives the plain version in its guidance on HRT side effects: there is little evidence that most types of HRT make you put on weight, and weight changes around menopause happen whether you take HRT or not.⁴
NHS, side effects of HRT

The patch was the new thing in those three months. So it got the blame.

Before you stop HRT because of the scale

Stopping is your decision, and it is a legitimate one. It is also worth making on the right information.

If you started hormone therapy for night sweats, hot flashes or broken sleep, and those improved, stopping it will not reverse the midlife weight trend the trials describe, because the therapy was not causing it.¹² What stopping is likely to do is bring back the symptoms you started it for. For many women, that means the sleep goes again, and short sleep has its own effect on appetite.

The more useful conversation is usually about the composition change underneath, the lean mass that starts slipping at exactly this stage, and what to do about it.³ That is a strength and protein question far more than a hormone question.

When this belongs with a doctor

Talk to your prescriber before stopping or changing any hormone therapy. Get checked promptly for rapid unexplained weight gain, swelling in the legs or ankles, breathlessness, or pain and swelling in one leg, none of which should be put down to midlife. Side effects that have not settled after about three months are also worth raising, since a different dose, type or route may suit you better.

The sentence to take with you: “I have gained a few pounds since starting, mostly around my waist. The trials say HRT does not cause weight gain, so can we look at what else is changing, including muscle, and decide whether this regimen is still right for my symptoms?”

The one move: measure the right thing for twelve weeks

Put the scale in the cupboard for three months. Not forever. Just long enough to stop it running the decision.

Instead, once a fortnight, measure your waist at the navel with a soft tape, same morning, same spot, and write it next to a single line about your sleep and hot flashes that week.

The waist is where the transition actually shows its hand.² Next to it, the symptom line keeps the other half of the ledger visible: the reason you started. At twelve weeks you walk into your review with two columns instead of one frightening number, and the conversation about whether to continue becomes a decision rather than a reflex.

Common questions

Does HRT cause weight gain?

The best evidence says no. A Cochrane review of 28 randomized trials in 28,559 women found no evidence that estrogen alone or combined with a progestogen affected body weight or BMI beyond the usual gain around menopause.¹

Does estradiol cause weight gain?

Estradiol is the estrogen used in most modern HRT, and the trial evidence does not show it causing weight gain. The International Menopause Society’s review found that studies mostly indicate a reduction in overall fat mass with estrogen therapy.²

Does estrogen cause weight gain or belly fat?

The hormonal changes of menopause itself are associated with more abdominal fat.² Taking estrogen as therapy has not been shown to add weight, and studies mostly point toward lower overall fat mass on treatment.²

Why am I gaining weight in perimenopause if it is not the hormones?

Midlife women gain about half a kilogram a year with age.² During the transition, the rate of fat gain doubles while lean mass starts to fall, which changes shape more than weight.³

Will stopping HRT help me lose weight?

The trials give no reason to expect it, since hormone therapy did not cause the gain in the first place.¹ Stopping is likely to bring back the symptoms you started it for, so it is a decision to make with your prescriber.

Weight is the change you can measure, which is why it dominates the conversation about HRT. The changes women report as more disruptive are harder to weigh: memory, concentration and mood during the transition.

The one move

For twelve weeks, skip the scale. Every two weeks, write down your waist measurement and one line about sleep and hot flashes. Take both columns to your review.

If the weight is one of several things you have been carrying quietly this year, seeing them all together tends to make the next decision easier. Start here.

The patch is doing the job you gave it. The waistband is a different story, and it has a different fix.

On the researchers. Susan Davis is an endocrinologist and researcher, not your prescriber; the review she led summarizes evidence across populations and cannot tell you how any single product will affect you. Gail Greendale is cited for the SWAN body composition study. Robert Norman is cited as a senior author of the Cochrane review.

Sourcing, disclosure and disclaimers

This is not medical advice. Blue Leaf Journal publishes general information for a general readership. Nothing here is a diagnosis, a treatment recommendation, or a substitute for care from a clinician who knows your history. Informational, not medical advice: see your clinician.

We are not clinicians. Blue Leaf Journal is an independent publication and its bylines carry no medical or academic credential. We read published research and translate it. The findings belong to the researchers and institutions named and linked above; the plain-English rendering is ours, and so is any error in it.

No affiliation and no endorsement. Blue Leaf Journal is not affiliated with Susan R. Davis, Gail A. Greendale, Robert J. Norman, Eugene Kongnyuy, Monash University, the International Menopause Society, UCLA, the University of Adelaide, Cochrane, the Study of Women’s Health Across the Nation or the NHS. None of them has reviewed, approved or endorsed this article, and none of them is responsible for it.

No commercial relationship. Nobody named above paid for or was paid for this coverage. There are no affiliate links, no sponsored placements and no product recommendations in this article.

How this was checked. Every figure above was checked against the cited source on 16 September 2026, and each source is linked below. If you find something we have got wrong, write to norawhitfield@blueleafjournal.com and we will correct it and say that we did.

References
1. Kongnyuy, E. J., Norman, R. J., Flight, I. H. K., Rees, M. C. “Oestrogen and progestogen hormone replacement therapy for peri-menopausal and post-menopausal women: weight and body fat distribution.” Cochrane Database of Systematic Reviews, CD001018. Cochrane summary
2. Davis, S. R., Castelo-Branco, C., Chedraui, P., et al. “Understanding weight gain at menopause.” Climacteric, 2012, 15:419–429. PubMed · free full text via the International Menopause Society
3. Greendale, G. A., et al. “Changes in body composition and weight during the menopause transition.” JCI Insight, 2019. JCI Insight · free full text via PubMed Central
4. NHS, “Side effects of hormone replacement therapy (HRT)”.

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Nora Whitfield writes for Blue Leaf Journal, where the working rule is that a mechanism you can name is easier to live with than one you cannot. She reads the limitations section before the conclusion, and passes on what she finds there.

Written by Nora Whitfield for Blue Leaf Journal. Updated: 16 September 2026.