Saw the new Lancet meta-analysis on lean mass loss with GLP-1s. They pooled 12 trials, n=3,400, and report lean mass was about 15% of total weight lost on average.
I'm 22 weeks in, down 28 lbs, and my InBody says lean mass down 4.1 lbs. That's roughly 15%, right? But InBody is noisy. Is the news framing this as muscle wasting, or is it mostly expected from any rapid weight loss? Not asking for medical advice, just trying to read the data.
I read the same Lancet paper. The 15% is lean mass share of total loss, not 15% of your starting lean mass. Big difference.
Headlines keep saying 15% muscle loss. Denominator matters.
InBody can swing 3-4 lbs with hydration. I did DEXA at week 0 and week 24: 31 lbs total loss, 5.2 lbs lean loss, so similar ratio. The paper noted some lean loss in diet-only arms too.
DEXA is the only way I'd trust that. My smart scale said I lost 6 lbs lean and I panicked alot.
The hydration point matters, but the bigger issue is that lean mass isn't the same as skeletal muscle.
The meta-analysis measured lean soft tissue, which includes water and organ mass. A 15% ratio after big weight loss isn't automatically bad. I'd rather see grip strength and DEXA appendicular lean mass. The headlines are scary but the paper is more nuanced.
Grip strength is such a better marker than scale lean mass. My gym numbers actually went up.
Same. Deadlift PR while scale said lean mass tanked. Made me ignore InBody.
22 weeks and 28 down is about 1.3 lbs/week, so a 4.1-lb lean drop on InBody reads more like noise to me than muscle wasting—15% is a ratio, not a diagnosis. My surprise was the opposite of what I expected: my InBody looked worst around month 3, then at month 6 my waist was down 4.5 inches and I could do 3x10 goblet squats with 30 lbs instead of 15, even though the scale kept dropping and the lean number bounced around.
I stopped weighing after a stomach bug because it claimed I lost 5 lbs of lean in two weeks, which was clearly dehydration. What actually helped me judge it was waist tape, how my jeans fit, and one strength benchmark once a week, same time, same conditions, plus comparing InBody only fasted and hydrated.
What’s your waist or clothing-fit trend been over those 22 weeks?
My InBody swung 5.2 lb of “lean mass” between scans 10 days apart—after a salty takeout weekend and a heavy leg day—while my waist tape barely moved, so I stopped treating one scan like a verdict. What actually tracked my 30-lb loss on this was a cheap tape at the navel, how my jeans fit across the butt/thighs, and whether I could do my uual 30-minute walk without my hips yelling.
The weird reversal: I added two 20-minute dumbbell circuits a week and a protein-forward breakfast, my next scan looked flat-to-worse on lean, but I went from 8 to 14 pushups and dropped another belt notch; the scary number wasn’t the one that changed my body. At 22 weeks I’d care less about the 15% and more about whether your waist, grip, and stairs are holding steady—if they are, that headline is mostly the usual cost of fast loss, not automatic muscle wasting.
tbh yeah, 4.1/28 is ~15%. But that’s share of total pounds lost, not share of your lean mass. Huge difference.
4 lb off a 200-lb frame is ~2%. Off a 140-lb frame it’s ~3%. Neither screams wasting by itself.
The meta is averages, not your scan. I’d track absolute lean and waist over 8–12 weeks.
What was your starting weight? That changes the read.
Did the meta-analysis report appendicular lean mass or total lean mass? That distinction is the whole panic dial.
Total lean includes organs, skin, connective tissue, and water; appendicular lean is the closer proxy for skeletal muscle. If they pooled total lean, 15% is mostly expected partitioning.
If appendicular, I’d want the ALM/height² or ALM/weight numbers.
Did the paper break that out, or is everyone arguing about a blended bucket?
I’m about 9 months in and down 51 lb. My DEXA at month 4 had lean mass down 3.8 lb, but my grip strength and goblet squat were up, so my NP and I watched function more than the number.
What helped me was a boring protein anchor at breakfast (~30g) and two full-body lifts a week; last two scans my lean mass has been basically flat. Did the meta-analysis break out resistance-training vs. not? That’s the subgroup I’d want before reading 15% as muscle wasting.
InBody gets moody on me too—mine jumps after a salty supper, so I only trust trends. Hugs!
One thing I’d want the meta-analysis to break out: how much lean loss happens in the first 12–16 weeks vs after weight stabilizes. My scan was ugliest during the rapid-loss phase, then leveled off even as the scale kept creeping.
With two kids and chaotic dinners, my hedge is a snack drawer with pre-portioned edamame, cottage cheese, turkey sticks, plus a resistance band by the kettle. Not perfect, but I can actually do 5 minutes while the pasta boils. Did the paper report timing or just total?
sharp follow-up: did the meta-analysis look at strength outcomes, not just lean mass? I’m on one of thee meds too, down 31 lb, and my InBody lean drop of 3 lb spooked me until I started tracking grip strength and 30-second chair stands.
My scan wobbled but my chair stands got easier, so I quit obsessing over the lean percentage. Our local pharmacy’s dietitian mentioned that number can include water and glycogen shifts, too. Are you doing any functional strength checks alongside the InBody?
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