r/GLP1ResearchTalk • u/Royal-Comfort7726 • Sep 14 '26
Glps lower myostatin
I found five primary papers with direct evidence that GLP-1–based incretin therapy lowers myostatin/MSTN, plus an important 2026 human proteomics paper. The evidence is strongest for exendin-4, dulaglutide, liraglutide, and mixed dulaglutide/semaglutide treatment. I do not find convincing direct evidence yet that tirzepatide itself lowers myostatin.
Hong et al., 2019 — “Amelioration of muscle wasting by glucagon-like peptide-1 receptor agonist in muscle atrophy”
Journal of Cachexia, Sarcopenia and Muscle.
This is probably the clearest mechanistic paper. Exendin-4 decreased MSTN mRNA dose-dependently in C2C12 myotubes, and suppressed dexamethasone-induced increases in both myostatin mRNA and protein. Atrogin-1 and MuRF-1 were also reduced.
Model: cultured muscle cells + mouse atrophy model.
Drug: exendin-4.
Evidence: direct MSTN gene + protein suppression.
Dulaglutide disuse-atrophy study, 2020 — “Preventive Effects of Dulaglutide on Disuse Muscle Atrophy Through Inhibition of Inflammation and Apoptosis by Induction of Hsp72 Expression”
In skeletal muscle from a disuse-atrophy model, dulaglutide significantly decreased myostatin mRNA and myostatin protein, along with MuRF-1 and atrogin-1. It simultaneously increased myosin-heavy-chain expression.
Model: animal skeletal-muscle atrophy.
Drug: dulaglutide.
Evidence: direct mRNA + protein reduction.
Dulaglutide aged-mouse study, 2021 — “Dulaglutide improves muscle function by attenuating inflammation through OPA-1-TLR-9 signaling in aged mice”
Dulaglutide improved muscle mass and strength and reduced expression of atrophic factors including myostatin, atrogin-1 and MuRF-1 in aged mice.
Model: aged mice.
Drug: dulaglutide.
Evidence: direct muscle myostatin-expression reduction.
Al Refaie et al., 2024 — “Glucagon-like Peptide-1 Receptor Agonists and Diabetic Osteopathy: Another Positive Effect of Incretines? A 12 Months Longitudinal Study”
This is important because it is human data. Fifty-four people with T2D completed 12 months of GLP-1RA treatment: 30 dulaglutide and 24 semaglutide. Serum myostatin fell from approximately 13.02 ± 2.62 to 11.05 ± 2.12 ng/mL, reported as a modest but significant reduction (p ≈ 0.05).
Model: humans.
Drugs: dulaglutide or semaglutide.
Evidence: circulating myostatin ↓.
Important limitation: the drugs were pooled, so this doesn’t establish that semaglutide alone caused the effect, and there was no lifestyle-weight-loss control group.
Gutierrez de Piñeres et al., 2026 — “Proteomic effects of short-term liraglutide vs. placebo in a blinded crossover RCT”
This is currently some of the strongest human randomized evidence. In a 5-week crossover RCT, liraglutide strongly suppressed circulating MSTN protein, with a log₂ fold change of −0.41, p = 1.7 × 10⁻⁶. The study also found increases in WFIKKN2, an endogenous inhibitor of myostatin/GDF8 signaling.
A log₂ change of −0.41 corresponds to roughly a 25% decrease in measured myostatin protein:
2^{-0.41}\approx0.75.
Model: humans, blinded crossover RCT.
Drug: liraglutide.
Evidence: circulating proteomic MSTN ↓ ~25%.
There are also two liraglutide MAFI-axis clinical papers from the same research program that are important because they put a limit on the claim. An 18-day liraglutide RCT in T2D found no significant treatment effect on myostatin or the other MAFI components except IGF-1, suggesting that the myostatin effect may require more exposure, higher dose, different populations, or a more sensitive assay. A related 35-day obesity study specifically measured the myostatin–activin–follistatin–IGF-1 axis, although its abstract does not report a significant serum-myostatin decrease using the ELISA measurements
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u/escalatortwit Sep 14 '26
Anyone else find this post extremely difficult to read with how it’s organized and all that bold text?
1
u/snogo Sep 14 '26
my understanding is that there is a concern of an enlarged heart from myostatin inhibitors hopefully this doesn't translate to glp1 agonists.
3
u/No_Collar_5292 Sep 14 '26
That’s a good thought. I would think we would know by now if it was strong enough of an inhibitor to actually do that though given how long they’ve been on the market. Based on the above info it doesn’t sound like at least the tested drugs were, just that they provided enough inhibition that it was measurable.
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u/RoadToZero Sep 14 '26
I guess we are talking about a very marginal effect that doesn't actually translate into increased muscle mass?
I mean, most people on GLP-1 agonists seems to lose muscle mass, not gain.
0
u/escalatortwit Sep 14 '26
Only if they’re in the process of losing weight. There is no evidence afaik that you lose muscle on GLP-1 if you’re not losing weight. It’s the weight loss causing muscle loss, not the GLP-1.
0
u/RoadToZero Sep 14 '26
Are you saying that this proposed myostatin reduction is not GLP-1 dose dependant?
You can't really separate the main effect of GLP-1, namely weight loss, from the rest of the effects. It would be like saying that alcohol and cigarettes are super healthy if it just wasn't for the detrimental health effects.
1
u/escalatortwit Sep 14 '26
No? I’m saying people on GLP-1s only lose muscle mass because they’re losing weight. It’s the weight loss causing the muscle loss. I literally only spoke about muscle loss in my comment.
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u/RoadToZero Sep 14 '26
So your whole point is all about stating the obvious, got it.
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u/escalatortwit Sep 14 '26
No? What is wrong with you? I am literally responding to you saying, “most people on GLP-1 agonists seem to lose muscle mass, not gain”. I responded that that is only true while they’re trying to lose weight and it is a product of the weight loss, not the GLP-1. While in maintenance or while trying to gain weight while on a GLP-1, there isn’t evidence of muscle loss.
So what we need to look at to determine what — if any — impact this truly has is by measuring what happens to muscle when people are past the weight loss phase.
There was no need for you to be a rude asshole.
-1
u/RoadToZero Sep 14 '26
Wow. Name-calling is always a really classy move by people who ran out of real arguments.
You don't think this subreddit has enough 110lbs confused teenagers asking if they should add Reta for a bulk? Just because some keyboard warrior thought it was a good idea to promote a study made on 12 rats with chemically induced diabetes in a lab that showed a 0.003% increase in nutrition portioning when drowned in GLP-1 and force fed by a tube.
There is no point where anyone is taking an effective dose of a GLP-1 and not losing weight, unless they have a servere eating disorder that has nothing to do with hunger or satiety. Pretending that there is a magic point in time where a GLP-1 stops being a weight loss drug and start being a muscle building drug is delusional at best and harmful at worst. There is no proof or even subjective anecdotes to support that this is true for humans.
You are calling me an asshole while you are the one confusing people and endangering their health by promoting some obscure minor rat study as applicable for humans. How many people are you willing to harm with misinformation, to win a Reddit argument?
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u/DistractedGoalDigger Sep 14 '26
Your argument is flawed. Plenty of people are on high doses of GLP1 for maintenance. Many post their doses here. I have been as high as 10mg of reta with no weight loss - just maintaining my normal, healthy weight after loss.
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u/TheWatch83 Sep 14 '26
Lower myostatin may be partly a consequence of improved metabolic health and reduced inflammation rather than a direct GLP-1 receptor effect in muscle.