Dr.RenalNash said:

The honest range is roughly 20 to 40% of total loss as lean mass without deliberate resistance training, and roughly 10 to 20% with it plus adequate…

This is exactly what I could not find anywhere else. Sending this to two other people who asked me the same thing last week.

Clinical perspective, offered as context rather than as advice.

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:

1. Food diary review — is intake creeping up?
2. Protein check — minimum 100g/day
3. Activity audit — steps + resistance training
4. Sleep quality — poor sleep kills GLP-1 efficacy
5. Stress/cortisol management

Only after addressing all of these do we increase the dose. Often fixing one lifestyle factor restarts progress without needing more medication.

Dr.SportsMedIN said:

Physical therapist weighing in on lean mass.

Dr.SportsMedIN 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.

MikeFit_NJ said:

There is also a quality change that the scan cannot see.

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

Moderator note: leaving this open. It is being argued well and the disagreement is the useful part. Carry on.