Is there a drug that stops muscle loss on a GLP-1?

Yes — several, and none of them are available to you. That is the whole answer in one line, and the rest of this page is the detail behind it.

As of September 2026 there are at least four drug programmes whose specific purpose is to stop you losing muscle while a GLP-1 takes your weight down. All are in Phase 2. None is approved for this use. None can be prescribed for it.

Why this is happening at all

The problem is real and large enough that several companies are spending heavily on it. Estimates of how much of GLP-1 weight loss is lean tissue run from roughly a quarter to as much as 40%, and at the totals these medications produce — 15% to 21% of body weight — that is a great deal of tissue.

If nothing else, the size of this pipeline settles the question of whether the concern was overblown. It was not.

What is actually in development

Bimagrumab. The furthest along in published evidence. The BELIEVE trial ran 72 weeks and reported in Nature Medicine in March 2026. Given with semaglutide it produced 22.1% weight loss with 92.8% of it coming from fat — against 71.8% for semaglutide alone. On its own, bimagrumab increased lean mass by 2.5%. There is a fuller write-up here.

Trevogrumab. Regeneron’s myostatin antibody, in the COURAGE trial with semaglutide. Interim results reported preserving between 50% and 80% of the lean mass that semaglutide alone would have cost. A three-drug version adding garetosmab reached 80.9%. The trial is due to complete late in 2026.

Apitegromab. Scholar Rock’s myostatin inhibitor, tested with tirzepatide in the EMBRACE trial — 102 participants over 24 weeks, with roughly 55% relative preservation of lean mass against tirzepatide plus placebo, at similar total weight loss.

Enobosarm. Veru’s candidate, a selective androgen receptor modulator rather than a myostatin blocker — a different mechanism aimed at the same outcome. In Phase 2.

Several others are earlier still: garetosmab, SRK-439, taldefgrobep alfa.

What “Phase 2” actually means for you

It means these are being tested for whether they work and are safe enough to test further. It does not mean they are coming soon.

A Phase 2 result has to be confirmed in larger and longer Phase 3 trials, then reviewed by regulators, then priced, then covered by insurers or paid for out of pocket. Each of those stages takes time and each is a place where a drug can stop. Plenty do.

These are also all combination therapies — an additional injection or infusion on top of a GLP-1 you are already paying for. Bimagrumab in BELIEVE was given intravenously every 12 weeks. Even in the best case this is not a pill you add.

The question nobody has answered yet

Every result above is measured on a scan. They show more lean mass retained.

What is not yet established is whether that translates into the things you would actually want from it — being stronger, functioning better, staying healthier for longer. Lean mass on a DXA report and useful muscle are related but not identical, and the trials so far are too short to show outcomes rather than measurements.

This is not a reason to dismiss them. It is a reason to be careful about how much is claimed, and it is the honest state of the evidence today.

What this means if you are taking a GLP-1 now

Nothing changes about what you can do. The two things with evidence behind them today are the same two things as before: eat enough protein and do resistance training two or three times a week. Both are free, available now, and carry no approval risk.

It is also worth noting what the trials keep showing about that. In BELIEVE, bimagrumab given on its own raised lean mass by 2.5% — a pharmaceutical achieving what resistance training achieves in people who start doing it. The drug is not doing something unavailable to you. It is doing it without the training.

If you want to know where you currently stand, the muscle check will estimate your own split and name which of the two levers is costing you most.

If you are considering waiting

Some people read pipeline news and conclude they should hold off starting a GLP-1 until the combination exists. That is a real decision with real trade-offs, and it is covered separately in should you wait for a muscle drug. The short version is that “years away” is doing a lot of work in that plan, and it is a conversation for your prescriber rather than a calculator.