Women on GLP-1s Are Weighed Constantly. Their Strength Rarely Is.

By Taylor Walder, Journal Editor

Party season is coming. So are the photos, and the questions: what did you lose, what do you weigh, what did the scale say this morning. For more women in midlife, the answer now involves a GLP-1.

Everyone watches the scale. According to the researchers cited below, the number that gets far less attention is strength.

Some GLP-1 medicines are approved for type 2 diabetes and some for weight management. Which use is approved depends on the product and the country. Using one outside its approved use (off-label) is a decision for a prescriber. This article doesn't recommend any product, dose, or starting or stopping a medication.

Who is taking GLP-1 medicines

According to a 2025 RAND survey of 8,793 US adults, 11.8% said they had ever taken a GLP-1 medicine. Among women aged 50 to 64, the figure was 20%, the highest of any age and sex group in the survey. RAND's authors note that the figures are self-reported (RAND RR-A4153-1, 2025).

That age band overlaps with the menopause transition. In the Study of Women's Health Across the Nation (SWAN), published in JCI Insight in 2019, researchers timed body-composition change to each woman's final menstrual period. They reported that lean mass began to fall at the start of the transition and kept falling until about two years after the final period, then levelled off. A Finnish follow-up of 234 women aged 47 to 55, published in the Journal of Clinical Medicine in 2020, reported the same direction of change and found physical activity was associated with keeping more lean mass. Both studies were observational.

What the trials measured

The large GLP-1 trials did look at muscle-related tissue, through DXA body scans in smaller groups of participants.

In the STEP 1 trial of semaglutide, published in the New England Journal of Medicine in 2021, people on semaglutide lost 14.9% of body weight on average over 68 weeks, compared with 2.4% on placebo, alongside a lifestyle programme. In a STEP 1 substudy that scanned body composition (DXA), about 5.3 kg of the 13.6 kg lost was lean mass, roughly 38%, as reported in a 2025 joint advisory. The trial was funded by Novo Nordisk, and three of its authors were company employees.

In a body-composition substudy of the SURMOUNT-1 trial of tirzepatide, published in Diabetes, Obesity and Metabolism in 2025, 160 participants were scanned. The authors reported that about a quarter of the weight lost was lean mass, and that the proportion was similar in the placebo group. Most of the authors were Eli Lilly employees, and the paper carries a published erratum.

What the scans cannot tell us

These figures come with caveats that rarely travel with them. In both trials, these were body-composition measurements in smaller scanned subgroups (160 people in SURMOUNT-1), not the trials' main outcomes.

A 2024 narrative review in Diabetes, Obesity and Metabolism by Neeland and colleagues points out that scan-measured "lean mass" includes organs, bone and water as well as muscle. The same review reports that the lean share of weight lost has ranged from about 15% or less in some studies to 40–60% in others, depending on the population and the method.

None of these analyses measured whether participants could climb stairs, rise from a chair or carry shopping as easily as before. A scan can show tissue moving. It does not show function.

Why researchers look at strength

Strength tests have a long research record as markers. According to a 2010 meta-analysis in The BMJ by Cooper and colleagues, people with weaker grip, slower walking, slower chair rising or poorer balance had a higher risk of death from any cause during follow-up. In the PURE study, published in The Lancet in 2015, each 5 kg lower grip strength among almost 140,000 adults in 17 countries was associated with a 16% higher risk of death from any cause.

The authors of both studies describe associations. These findings do not show that a weak grip causes harm or that a stronger one adds years. They show that a quick test carries information.

What a 2025 advisory recommends

In 2025, four US societies (the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society) published a joint advisory on nutrition during GLP-1 therapy. Among its priorities when someone starts treatment, the advisory lists a baseline "muscle strength, function, and body composition assessment".

That is a recommendation addressed to clinicians, and the advisory frames it as part of care planned with a prescriber.

The limits of the simple tests

Common strength tests include the 30-second chair stand, grip strength and timed walks. Researchers flag two limits.

The first is who the charts were built for. The 30-second chair stand was validated by Jones, Rikli and Beam in 1999 in 76 adults over 60, with an average age of about 70. The standard norm tables from Rikli and Jones, published the same year, cover ages 60 to 94. Reference values for younger adults exist, including those from the 1000 Norms Project published in Neurology in 2017, but, in our editorial view, these tables were built from people tested by trained assessors, not from women testing themselves at home.

The second is noise. In a 2022 study in Physiotherapy Research International, Gill and colleagues tested adults with early-stage knee osteoarthritis and reported that an individual's chair-stand count had to move by about 2.5 stands before the change could be told apart from measurement error. That group was supervised and was not made up of midlife women testing at home; we did not find comparable data for that group. So, compare with your own earlier results, not with a table.

The question worth asking

Taken together, the sources above suggest a narrower question than "Is my number good?" It is closer to: has my number moved by more than the test's typical noise, compared with my own starting point?

For anyone on a GLP-1, or thinking about one, that is a conversation to have with the prescriber, who can say what baseline, if any, makes sense for you.

Before the season gets loud

In the weeks before the holidays, the pressure tends to land on one number. The research summarised here shows how much that number leaves out.

If you want more evidence-first reading on strength, hormones and midlife, subscribe to the Female Reserve Journal or join the Female Reserve community. We read the studies so the caveats travel with the headlines.

Female Reserve provides general health information. It does not diagnose, treat or replace care from a qualified professional. If you are worried about a symptom, speak to a clinician. If you take or are considering a GLP-1 medicine, ask your prescriber what applies to you.

Reviewed: 27 Oct 2026, Victoria Grant (AI evidence review)

Understand the system. Protect your Reserve.

Sources

1. Bozick R, Donofry SD, Rancaño KM. New Weight Loss Drugs: GLP-1 Agonist Use and Side Effects in the United States. RAND RR-A4153-1, 2025. https://www.rand.org/pubs/research_reports/RRA4153-1.html
2. Greendale GA, et al. Changes in body composition and weight during the menopause transition. JCI Insight 2019;4(5):e124865. https://doi.org/10.1172/jci.insight.124865 · https://pubmed.ncbi.nlm.nih.gov/30843880/
3. Juppi HK, et al. Role of menopausal transition and physical activity in loss of lean and muscle mass. J Clin Med 2020;9(5):1588. https://doi.org/10.3390/jcm9051588 · https://pubmed.ncbi.nlm.nih.gov/32456169/
4. Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med 2021;384:989–1002. https://doi.org/10.1056/NEJMoa2032183 · https://pubmed.ncbi.nlm.nih.gov/33567185/ (COI: Novo Nordisk funded; 3 employee authors)
5. Look M, et al. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study. Diabetes Obes Metab 2025;27(5):2720–2729. https://doi.org/10.1111/dom.16275 · https://pmc.ncbi.nlm.nih.gov/articles/PMC11965027/ (COI: most authors Eli Lilly employees; erratum doi 10.1111/dom.70050)
6. Neeland IJ, Linge J, Birkenfeld AL. Changes in lean body mass with GLP-1-based therapies and mitigation strategies. Diabetes Obes Metab 2024;26(Suppl 4):16–27. https://doi.org/10.1111/dom.15728 · https://pubmed.ncbi.nlm.nih.gov/38937282/
7. Cooper R, et al. Objectively measured physical capability levels and mortality. BMJ 2010;341:c4467. https://doi.org/10.1136/bmj.c4467 · https://pubmed.ncbi.nlm.nih.gov/20829298/ (observational)
8. Leong DP, et al. Prognostic value of grip strength (PURE). Lancet 2015;386:266–273. https://doi.org/10.1016/S0140-6736(14)62000-6 · https://pubmed.ncbi.nlm.nih.gov/25982160/ (observational)
9. ACLM, ASN, OMA, TOS joint advisory. Nutritional priorities to support GLP-1 therapy for obesity. Obesity Pillars 2025 (also the source for the STEP 1 DXA figure: 5.3 kg of 13.6 kg lost was lean mass). https://doi.org/10.1016/j.obpill.2025.100181 · https://pmc.ncbi.nlm.nih.gov/articles/PMC12264624/
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