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

What training is actually for during a large deficit, because framing it as calorie burn sets people up to quit when the arithmetic disappoints them?

SurmountFan_IN said:

My endo's protocol for lean mass plateau: if weight loss stalls for 6+ weeks at current dose, we go through this checklist before titrating up: Food…

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

SurmountFan_IN said:

My endo's protocol for lean mass plateau: if weight loss stalls for 6+ weeks at current dose, we go through this checklist before titrating up: Food…

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].

SurmountFan_IN said:

My endo's protocol for lean mass plateau: if weight loss stalls for 6+ weeks at current dose, we go through this checklist before titrating up: Food…

That reframing is the part I needed. Adding it to my notes with a link back to this thread.

Adding the clinical framing, because it changes how the question reads.

Sharing my comprehensive lab data relevant to lean mass:

Protocol: Tirzepatide 15mg/wk, resistance training 4x/week, protein 1.6g/kg/day.

The improvements in lean mass are clearly reflected in these numbers. The inflammatory marker reduction (hsCRP) is particularly striking.