Losing weight.
Keeping more muscle.
A new study asks whether people taking semaglutide, a GLP-1 medicine used for weight management, can lose weight while keeping more muscle. Here’s what the results mean.
The short version
Regeneron, the study sponsor, reports that its experimental medicine trevogrumab reduced the loss of lean mass—muscle and other soft tissue—over one year. Total weight loss was not meaningfully greater. The combination is not an approved treatment. [1]
Why this matters
Muscle helps us get out of a chair, climb stairs and carry groceries. Keeping muscle and strength becomes especially important as we age. [3]
That makes the question behind this study easy to understand: when someone loses weight, what are they losing—and what are they keeping?
What changed after one year?
The comparison below comes from the lower-dose part of the Phase 2 COURAGE trial in adults with obesity. Both groups received semaglutide. [1]
Measured by DXA body-composition scans. These are group averages, not an individual prediction. [1]
The difference is 3.1 percentage points, or about 43% less lean-mass loss relative to the comparison group. Some lean mass was still lost.
And the “almost 70%” finding?
That comes from a separate MRI analysis of participants with usable scans. The 75 mg group had 68.9% less thigh-muscle volume loss than the comparison group. It does not mean a 70% increase in muscle. [1]
Keep the measurements separate: “lean mass” includes muscle and other tissue; the MRI analysis looked specifically at thigh muscle volume. Neither number, on its own, tells us how much stronger someone became.
What we still need to know
Better scan results are encouraging. The practical questions are whether people also become stronger, move more easily and stay healthier over time. Those benefits cannot be assumed from these numbers.
Trevogrumab remains experimental. COURAGE is a randomized Phase 2 study designed to examine both benefits and safety. [2] The October 1 results were reported by Regeneron; its release described the paper as in press at The Lancet. [1]
Look closer at the study
The 52-week comparison used semaglutide 2.4 mg with placebo or trevogrumab 25 mg or 75 mg. These are trial doses, not instructions for use. [1]
| Added to semaglutide | Average change |
|---|---|
| Placebo | −7.3% |
| Trevogrumab 25 mg | −5.8% |
| Trevogrumab 75 mg | −4.2% |
Common reported side effects included nausea, constipation, diarrhea and vomiting. A one-year trial cannot settle long-term safety. [1]
This article covers the lower-dose, year-long comparison. COURAGE also studied other treatment groups; their results should not be mixed together.
A useful question to take away
“If I’m losing weight, how are we checking my strength and physical function—not just the number on the scale?”
This article explains research. Decisions about your treatment belong in a conversation with your clinician.
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Read the sources
- Regeneron’s COURAGE resultsOctober 1, 2026 · Sponsor announcement with the DXA and MRI results.
- COURAGE study registrationClinicalTrials.gov · NCT06299098 · Study design and experimental treatments.
- Why muscle and strength matter as we ageNational Institute on Aging · Background reading.
Sources checked October 6, 2026. The results above are attributed to the sponsor announcement; this article does not claim an independent review of the full trial paper.