I’ve lost single digit percentage lean mass vs total mass over the last thirty something pounds as indicated by sequential DEXA scans.
When I prioritized protein, I lost even less lean mass than when I didn’t.
Theoretically “anti-catabolic/lean sparing in varying degrees” supplements I use
TRT
Reta
HMB-FA
Creatine
Glycine
Taurine
That plus protein and lifting, for me, would practically stagnate losing actual contractile fiber.
When you first start losing weight the various forms of water weight (glycogen, inflammation, etc) that come off quickly in the first weeks are lean mass on a DEXA, but for the purposes of preserving muscle, it’s not important.