chris_chi24 said:Physical therapist weighing in on lean mass.
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].
[1] Pirkmajer S, et al. Front Physiol. 2023;14:1123456.
pam_columbus said:Agreed on the ranges, with the condition that a single DEXA is not a measurement, it is one draw from a distribution.
That reframing is the part I needed. Printing the relevant bit and taking it with me.
chris_chi24 said:Physical therapist weighing in on lean mass.
DEXA scan update relevant to lean mass:
Scanned at months 0, 6, and 12. Here are the body comp numbers:
| Baseline | Month 6 | Month 12 | |
|---|---|---|---|
| Total mass | 261 lbs | 226 lbs | 208 lbs |
| Fat mass | 111 lbs | 81 lbs | 43 lbs |
| Lean mass | 149 lbs | 148 lbs | 155 lbs |
| Body fat % | 38% | 34% | 22% |
Lean mass preserved — actually GAINED 1-2 lbs thanks to progressive overload + 1.5g/kg protein. The lean mass discussion needs to include body comp data, not just scale weight.
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Browse GL Biochemamsterdam_pete said:Two DEXA scans eleven months apart: down 24kg total, of which the scan says 6kg was lean.
Body composition tracking via bioimpedance on lean mass (InBody scan every 3 months):
| Metric | Baseline | Month 3 | Month 6 | Month 9 |
|---|---|---|---|---|
| Skeletal Muscle (lbs) | 71 | 71 | 68 | 71 |
| Body Fat (lbs) | 88 | 81 | 53 | 45 |
| Body Fat % | 39% | 34% | 26% | 21% |
| Visceral Fat (cm²) | 158 | 123 | 93 | 58 |
Note: skeletal muscle mass dipped initially then recovered with consistent resistance training + high protein. The visceral fat reduction is where the metabolic magic happens.