A sports medicine physician at New York's Hospital for Special Surgery has drawn a hard line between peptides with decades of human data and the recovery compounds sold through wellness clinics, in a Washington Post column summarized by Men's Journal. Jordan D. Metzl, MD, says the enthusiasm around peptides needs separating from what medicine actually knows.

Peptides are short chains of amino acids, and Metzl's point is that the word covers wildly different things. Insulin is a peptide-based medication. Semaglutide, the GLP-1 receptor agonist behind Ozempic and Wegovy, has been through large randomized clinical trials. BPC-157, TB-500, CJC-1295 and ipamorelin, all marketed for tendon healing, recovery, inflammation, muscle growth and fat loss, have not.

What a real trial looks like

Metzl cites a 2024 New England Journal of Medicine study in people with obesity and painful knee osteoarthritis, in which participants taking semaglutide for 68 weeks lost an average of 13.7 percent of body weight against 3.2 percent on placebo. Participants also reported substantially less knee pain and improved physical function.

For a sports medicine doctor, the interesting part is downstream of the scale: less weight can mean less joint pain, which makes movement possible for people who otherwise cannot exercise. That is a specific, measured, placebo-controlled finding, and it is the standard the rest of the category gets held to in this column.

Where the evidence stops

For the popular recovery peptides, Metzl says the available evidence consists largely of animal research, laboratory experiments, or very small human studies. That leaves open questions about effectiveness, dosing, which patients might benefit, and above all long-term consequences.

The FDA has raised concerns about limited safety information on many of these compounds because human exposure data remain scarce. Proposals about letting compounding pharmacies prepare certain experimental peptides have been floated on the argument that physician supervision beats the gray market, but as the column notes, compounding is not FDA approval and carries neither the same evidence nor the same manufacturing oversight.

Bottom line

Metzl's position is not that peptides should be abandoned: he argues they deserve more research, particularly for obesity, muscle preservation, pain reduction and healthy aging. His framing is the one worth keeping, which is that a laboratory effect, an animal result or a pile of online testimonials says nothing about what happens after five or 10 years of human use.