SarahChen_PharmD said:

Back pain as a lean mass side effect: not from the medication itself, but from rapid body composition changes.

Adding the part of the answer the thread has not reached. The dose-response is real but shallow at the top. Across STEP 1 and STEP 4 the gap between 1.7mg and 2.4mg is a couple of percentage points of body weight on average, and the average is carrying a wide spread — plenty of people at 1.7mg sit above the 2.4mg mean. If a dose is working and tolerable, "working" is the relevant variable, not "maximal".

SarahChen_PharmD said:

Back pain as a lean mass side effect: not from the medication itself, but from rapid body composition changes.

Regarding lean mass: I accidentally injected my dose intramuscularly instead of subcutaneously last week (went in at wrong angle, too deep). Called my pharmacist — they said it's not dangerous but may absorb faster, potentially causing more GI effects.

Sure enough, had worse nausea that day. Lesson learned: pinch the skin properly and use the right needle length for your body composition.

A narrower follow-up, since the general answer is now clear:

Whether anyone has held at a sub-maximal dose long term and kept the result, or whether the maintenance data only exists at 2.4mg?

Dr.PulmRoch said:

Regarding lean mass: I accidentally injected my dose intramuscularly instead of subcutaneously last week (went in at wrong angle, too deep).

Muscle fiber type changes during GLP-1-mediated weight loss, relevant to lean mass: preliminary biopsy data suggests that weight loss shifts the skeletal muscle fiber type distribution:

• Decreased Type IIx (glycolytic, fast-twitch) fibers
• Increased Type I (oxidative, slow-twitch) fibers
• Improved mitochondrial density and function
• Enhanced insulin-stimulated glucose uptake per fiber

This "metabolic remodeling" of muscle may contribute to improved insulin sensitivity independent of total lean mass changes. The muscle you keep becomes metabolically better, even if there's less of it[1].

Closing the loop on my own question.

Update. I did go to 2.4mg in the end, and the honest report is that it bought me less than the step before it and cost me two bad weeks. Worth knowing rather than worth repeating.