Dr.GutHealth said:

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

Back pain as a lean mass side effect: not from the medication itself, but from rapid body composition changes. Losing 67 lbs shifts your center of gravity and your core muscles need time to adjust.

Physical therapy has been essential. Core strengthening exercises (planks, dead bugs, bird dogs) daily for 10 minutes have eliminated my lower back pain. Your body is literally relearning how to carry itself.

RunnerRach said:

Agreed on the ranges, with the condition that a single DEXA is not a measurement, it is one draw from a distribution.

Saving this. It is the first explanation that did not require me to already understand it. Adding it to my notes with a link back to this thread.

Dr.GutHealth said:

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

DEXA scan update relevant to lean mass:

Scanned at months 0, 6, and 12. Here are the body comp numbers:

Lean mass preserved — actually GAINED 1-2 lbs thanks to progressive overload + 1.4g/kg protein. The lean mass discussion needs to include body comp data, not just scale weight.

hyun_seoul said:

Two DEXA scans eleven months apart: down 24kg total, of which the scan says 6kg was lean.

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.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Carry on.