# Do You Lose Muscle on a GLP-1? And What Comes Back Is Fat | This GLP A review reports lean mass losses of 6 to 7 kg during incretin therapy and fat-preferential regain averaging 5.6 kg within a year of stopping. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/do-you-lose-muscle-on-a-glp1 Updated: 2026-10-26 Published: 2026-09-16 [← Research](https://thisglp.com/research) Evidence # Do You Lose Muscle on a GLP-1? And What Comes Back Is Fat Six to seven kilograms of lean mass goes during treatment. About 5.6 kg comes back after stopping, preferentially as fat. The scale can read the same either way. [This GLP Editorial Team](https://thisglp.com/about)September 20266 min readUpdated September 2026 What comes off, and what comes back · on treatment · fat and 6–7 kg of lean mass · after stopping · 5.6 kg back, preferentially fat · The same weight, made of different tissue. · Figures gathered by a narrative review, not measured in it. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - A narrative review of what happens to body composition during and after incretin therapy. - It cites lean mass losses averaging 6 to 7 kg during active treatment, alongside falls in bone mineral density. - It cites post-cessation weight regain averaging 5.6 kg within a year, and describes that regain as fat-preferential. - So the tissue lost and the tissue regained are not the same tissue. - It also cites 85% of patients discontinuing within the second year of real-world use. Yes, and the tissue that comes back is not the tissue that left. A review of body composition during and after incretin therapy cites lean mass losses averaging 6 to 7 kg. Bone mineral density falls alongside it. After stopping, regain averages 5.6 kg within a year, and the review describes that regain as fat-preferential. Body-composition findings also depend on the clinical population. The [semaglutide studies in people living with HIV](https://thisglp.com/research/is-semaglutide-safe-for-people-with-hiv) address a distinct safety and fat-distribution question. So the scale can read the same at both ends of a course while the body underneath has changed. That is the finding, and it is not the one a weight chart shows. Several trials have tested a second drug to protect muscle. In 102 adults on tirzepatide, randomizing to add apitegromab held 1.9 kg more lean mass at 24 weeks [\[2\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-2). Total weight loss was similar in both arms, so [the lean mass was kept without blunting the loss](https://thisglp.com/research/can-a-drug-prevent-muscle-loss-on-a-glp1). Bimagrumab is the other candidate. It blocks the activin type II receptor, a signal that limits muscle growth. Given alone to 75 adults with type 2 diabetes, it added 1.70 kg of lean mass over 48 weeks [\[4\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-4). Lean mass on placebo fell 0.4 kg. No GLP-1 was used in that trial. A later trial paired it with semaglutide in 507 adults with obesity [\[5\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-5). At 48 weeks, weight fell 17.8 kg on the high-dose pair. It fell 14.2 kg on semaglutide 2.4 mg alone and 3.3 kg on placebo. The abstract reports weight as its endpoint. Lean mass is not among the results it gives. Two recent cohorts measured how the weight lost splits. In 35 adults on tirzepatide, fat made up 85.7 percent of the loss [\[6\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-6). Skeletal muscle fell 2.8 kg, or 8.3 percent. That clinic measured body composition by bioelectrical impedance. A second cohort matched 396 GLP-1 users to nonusers from connected-device data [\[7\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-7). Median weight fell 9.8 percent. Fat mass fell 7.5 percent and muscle mass 2.3 percent. Neither cohort was randomized. Bone runs the other way from what the review's density figures suggest. Pooled across twenty-five randomized trials, bone mineral density was higher on a GLP-1 at every site measured [\[3\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-3). Meanwhile [whether fractures fell is a question those trials cannot answer](https://thisglp.com/research/glp1-bone-density-vs-fractures). Weight coming back after stopping is well established and [covered elsewhere on this site](https://thisglp.com/research/what-else-comes-back-when-you-stop-a-glp1). This review is about something narrower and less discussed: what the returning weight is made of. ## What it gathers A narrative review searching three databases from 2005 to mid-2026, assembled under a standard framework for this kind of review. [\[1\]](https://thisglp.com/research/do-you-lose-muscle-on-a-glp1#ref-1) Every number in it is drawn from other studies rather than measured. A narrative review chooses what to include. These are figures it found, presented as it read them. On treatment, lean mass fell by 6 to 7 kg on average, alongside reductions in bone mineral density. After stopping, weight rose by 5.6 kg on average within one year, described as fat-preferential, with observational reports of dose-dependent cardiometabolic worsening. Why that combination matters more than either half Losing six kilograms of lean mass and regaining 5.6 kg of mostly fat does not return a person to where they started. The scale can read the same while the body underneath has less muscle and more fat. Lean mass determines resting energy expenditure. That makes the next attempt harder than the last. That is the argument for treating cessation as a clinical event rather than the absence of one. It differs from [what happens to muscle during treatment alone](https://thisglp.com/research/semaglutide-muscle-mass-and-grip). ## The persistence figure The review cites 85% of patients discontinuing within the second year of real-world use. That is the premise of the whole paper. If most people stop, what happens after stopping is most of the story. That figure comes from the literature the review surveys, not its own data. Persistence estimates vary with how long a gap counts as stopping. The direction is not in dispute. Do not quote the exact number as though it were measured here, any more than [a multiplier quoted without its base](https://thisglp.com/research/glp1-prescriptions-to-young-children) should. ## What it recommends, and what this page will not Structured exercise. Exercise and pharmacotherapy produce different body composition outcomes. Exercise preserves lean mass where the drug does not. The review offers prescription guidance. This page does not, because what is appropriate depends on age, joints, cardiac fitness and what somebody is already doing. What is safe to say is that the cessation transition has no established framework. The authors say so. Nobody selling a subscription is planning one, and [it is not among the things sellers publish](https://thisglp.com/tools/questions-they-leave-open). ## Frequently asked Is the weight that comes back the same as the weight that went? Not according to this review. Lean mass losses of 6 to 7 kg occur during treatment, while post-cessation regain averaging 5.6 kg is described as fat-preferential. Why does that matter if the scale reads the same? Because lean mass drives resting energy expenditure. Ending a cycle with less muscle and more fat than you started with makes the next attempt harder. How much of the weight lost on a GLP-1 is muscle? In two recent cohorts most of it was fat. On tirzepatide, fat made up 85.7 percent of the weight lost and skeletal muscle fell 8.3 percent. In connected-device data, median weight fell 9.8 percent, with fat mass down 7.5 percent and muscle mass down 2.3 percent. Can a second drug protect muscle? It has been tested. Adding apitegromab to tirzepatide held 1.9 kg more lean mass at 24 weeks. Bimagrumab alone added 1.70 kg of lean mass in adults with type 2 diabetes. Paired with semaglutide, it produced 17.8 kg of weight loss against 14.2 kg on semaglutide alone. How many people stop? The review cites 85% discontinuing within the second year of real-world use, drawn from the literature it surveys rather than measured in it. What should somebody do about it? The review argues for structured exercise, since exercise preserves lean mass where the drug does not. What is appropriate for a particular person is a clinical question. ## Sources 1. \[1\] Zeigler Z, et al. (2026). Structured Exercise During and After Incretin-Based Pharmacotherapy Discontinuation: A Narrative Review of Mechanisms, Evidence, and Prescription Guidance Healthcare. [PMID 42588312](https://pubmed.ncbi.nlm.nih.gov/42588312/) 2. \[2\] Pratley RE, Denham DS, Trivedi R, Watkins E, et al. (2026). Apitegromab for lean mass preservation during tirzepatide-induced weight loss: a randomized, double-blind, placebo-controlled phase 2 trial Nature Medicine. [PMID 42260100](https://pubmed.ncbi.nlm.nih.gov/42260100/) 3. \[3\] Tan Y, et al. (2025). Effect of GLP-1 receptor agonists on bone mineral density, bone metabolism markers, and fracture risk in type 2 diabetes: a systematic review and meta-analysis Acta Diabetologica. [PMID 39985672](https://pubmed.ncbi.nlm.nih.gov/39985672/) 4. \[4\] Heymsfield SB, et al. (2021). Effect of Bimagrumab vs Placebo on Body Fat Mass Among Adults With Type 2 Diabetes and Obesity: A Phase 2 Randomized Clinical Trial JAMA Network Open. [PMID 33439265](https://pubmed.ncbi.nlm.nih.gov/33439265/) 5. \[5\] Heymsfield SB, et al. (2026). Bimagrumab plus semaglutide alone or in combination for the treatment of obesity: a randomized phase 2 trial Nature Medicine. [PMID 41772149](https://pubmed.ncbi.nlm.nih.gov/41772149/) 6. \[6\] Corso H, et al. (2026). Effects of tirzepatide therapy on body weight and body composition in adults with overweight and obesity Frontiers in Endocrinology. [PMID 42488012](https://pubmed.ncbi.nlm.nih.gov/42488012/) 7. \[7\] Chabassier A, et al. (2026). Real-World Body Composition and Blood Pressure Changes Following Glucagon-Like Peptide 1 Receptor Agonist Initiation: A Causal Inference Study of Connected Device Data Mayo Clinic Proceedings: Digital Health. [PMID 42746268](https://pubmed.ncbi.nlm.nih.gov/42746268/) ## Where to get it ### Best GLP-1 injections Every injectable seller we can verify, with the price each one publishes and an honest read of what the trials measured. [Compare providers →](https://thisglp.com/best/compounded-semaglutide) ## More in Evidence - [ 150 minutes · Weekly activity goal · 2 days · Muscle strengthening · Adapt · Symptoms and ability ### Exercise on Ozempic: Building Strength Without Ignoring Symptoms ](https://thisglp.com/research/exercise-on-ozempic) - [ STEP 1, semaglutide 2.4 mg vs placebo, % change at 68 weeks · LDL cholesterol · −2.5% vs +1.3% · Total cholesterol · −3.3% vs +0.1% · HDL cholesterol · +5.2% vs +1.4% · Triglycerides · −21.9% vs −7.3% · Wegovy label, Table 13. Adults without diabetes. Ozempic doses are lower. ### Does Ozempic Lower Cholesterol? What the Lipid Results in the Trials Show ](https://thisglp.com/research/does-ozempic-lower-cholesterol) - [ Where the insulin reduction came from, units per day · week 4 · 13.4 total · week 26 · 21.9 · the drug itself · the weight loss · The drug’s own contribution barely moved: 11.1 then 11.4. · Everything added between weeks 4 and 26 came from weight. ### Does Semaglutide Help Type 1 Diabetes? What Two Small Trials Found ](https://thisglp.com/research/semaglutide-in-type-1-diabetes)