A Proportion That Rises by Itself

A study of 94 people taking compounded semaglutide at a commercial wellness studio reports that body composition improved, with gains in the overall proportion of lean muscle.^[1] Both halves of that are true. Doing the arithmetic on the same numbers shows that 35% of the weight they lost was lean tissue — and the proportion claim would have been true almost regardless.

The numbers, and what they sum to

Participants at a commercial wellness studio received weekly compounded semaglutide combined with cyanocobalamin, titrated from 0.25 mg toward 2.4 mg, and were measured at three months.

Fat and lean together account for essentially all of it — 2.67 plus 1.43 is 4.10, against a total of 4.11. So lean tissue made up roughly a third of everything lost.

Fat 2.67 kilograms. Lean 1.43 kilograms. Both went.

Why the proportion went up anyway

That is why the sentence is worth recognizing. “Body composition improved” and “the proportion of lean muscle increased” are the phrasings a marketing page lifts, and both are compatible with losing a third of your weight as lean tissue.

Is a third high? It is toward the upper end of what is usually described. The larger imaging evidence gives a more reassuring answer — in a trial that compared muscle loss against what population data predicted for the same weight change, the loss was no greater than expected and muscle quality improved more than expected. That work is in muscle volume versus muscle function, and it is a far better instrument than this study.

What this study is, exactly

• Ninety-four people, 81 of them women, average age 46.6.
• Retrospective, with no control group and no randomization.
• Three months, which is the steep early part of the curve.
• A commercial wellness studio, not a clinic or a trial site.

It is worth covering despite all of that, because it is the only real-world body composition data on a compounded product we have found. Almost everything known about what these drugs do to muscle comes from trials of the branded medicine at controlled doses. What happens with a compounded preparation obtained through a wellness studio has essentially not been studied.

The 4.57% at three months is modest and unremarkable for that point in a titration. It is a real result from real people, and it is not evidence about the compounded product specifically, because nothing here compares it to anything.

The B12 in the syringe

The product was semaglutide combined with cyanocobalamin — vitamin B12. Nothing in this study isolates one from the other, and nobody should read the result as evidence that adding B12 does anything.

There is no evidence base for B12 as a weight-loss agent. Its presence in compounded GLP-1 preparations has more to do with the rules governing what a compounder may prepare than with any expected benefit, which we set out in semaglutide compounded with B12.

What to carry away

• When you read that lean proportion improved, ask what happened in kilograms. The proportion rises on its own.
• Resistance training and adequate protein remain the answer, and nothing here changes that — see protein targets.
• A wellness studio is not a clinical setting. The result may be real and the context is not a trial.
• This tells you almost nothing about compounded product safety, which is a separate question with its own evidence.