From the other side of the consultation, briefly.

GenomicsKate said:

...the muscle loss concern with lean mass...

This is a legitimate and well-studied concern. Let me put some numbers on it:

In STEP 1, approximately 39% of weight lost was lean mass. However, the Lundgren 2024 study showed that structured resistance training reduced this to ~25% lean mass loss.

Context matters: at BMI 35+, you're carrying excess lean mass to support the extra weight. Losing some lean mass is expected and not inherently harmful if you maintain adequate muscle function through exercise.

The solution isn't avoiding the medication — it's combining it with proper exercise and protein intake.

Dr.PulmRoch said:

Body composition tracking via bioimpedance on lean mass (InBody scan every 3 months): Metric Baseline Month 3 Month 6 Month 9 Skeletal Muscle (lbs) 69…

OMG yes. lean mass + resistance training is the combo. Can confirm.

Dr.PulmRoch said:

Body composition tracking via bioimpedance on lean mass (InBody scan every 3 months): Metric Baseline Month 3 Month 6 Month 9 Skeletal Muscle (lbs) 69…

Thank you for spelling out the reasoning rather than just the conclusion. Adding it to my notes with a link back to this thread.

Clinical perspective, offered as context rather than as advice.

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].

Moderator note: two posts asking for a source have been merged into one. Please search the thread before asking again.