Free tool · For women on a GLP-1
How much of your
weight loss is muscle?
In studies, up to 40% of the weight lost on a GLP-1 can be muscle — not fat. Enter your numbers. See your estimate in about 10 seconds.
What do you weigh right now?
No judgment here. This number just sets the size of your estimate later.
How much have you lost — and how fast?
Two quick numbers: what you've lost so far, and how many weeks it's taken.
Are you following a protein plan from your dietitian?
Food is your dietitian's job — we just need to know if a plan is in place. It changes your estimate.
How do you move each week?
Tap the one that's most like your real week.
Quick strength check
How many times can you stand up from a chair in 30 seconds?
An educational self-check, not a medical test.
Stop right away if anything hurts.
Built from published GLP-1 trial data · An estimate, not a medical assessment
Your number is ready.
Knowing your number is how you stop losing muscle — and start building it back.
We handle the training. Your dietitian handles the food. Together, that's the whole fix.
Same weight loss — two very different results
Your full game-plan is ready — unlock it now and Email 1 lands in your inbox in about 2 minutes
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Built by Coach RJ — personal trainer for 16 years
Studies estimate 25–40% of weight lost on GLP-1s can be lean mass. This calculator estimates your share.
How it works
Enter your numbers
How much you weigh now, how much you've lost, how long you've been on your GLP-1, your protein, and whether you lift.
See how much could be muscle
Your estimate is built from published GLP-1 trial data — the same research your prescriber reads — adjusted for your protein and training.
Unlock the plan to protect it
What your number could drop to with lifting, the 3-step game-plan, and your protein plan — set by your dietitian — sent to your inbox, free.
Why this matters: muscle is what keeps you strong, firm, and able — and it's what protects you from regaining. The scale can't tell fat from muscle. This calculator gives you an honest estimate from the research, so you can protect the muscle you still have and rebuild what's already gone. It is never too late to start — muscle can be rebuilt at almost any age with strength training and enough protein.
Questions, answered
Why do women lose muscle on GLP-1 medications?
GLP-1 medications cut appetite hard, so total food — including protein — drops. When weight comes off fast and protein and strength training are missing, the body takes part of that weight from lean muscle, not just fat. In clinical trial analyses, roughly 25–40% of the weight lost can be lean mass when muscle isn't actively protected.
How much muscle can you lose on a GLP-1?
It depends on how much weight you lose, how fast, your protein intake, and whether you strength train. Without protection, studies suggest about 25–40% of weight lost can be lean muscle. With enough protein and regular resistance training, that share drops substantially — the calculator above estimates it for your numbers.
What are the signs you are losing muscle instead of fat?
The scale drops but your body looks softer, not firmer. Your butt flattens. Everyday strength fades — stairs, jars, and grocery bags get harder. And the loss is fast, more than about 2 pounds a week, with little or no strength training.
How much protein do you need on a GLP-1?
For women losing weight on a GLP-1, the 2025 joint advisory from leading nutrition and obesity organizations works out to roughly 0.55–0.75 grams of protein per pound of body weight per day, paired with resistance training. For many women that lands around 90–140 grams a day — your calculator result above gives your personal range.
What exercise prevents muscle loss on a GLP-1?
Progressive resistance training — lifting weights or using resistance bands 2–3 times a week — is the strongest protection, combined with adequate protein. Walking is healthy, but it doesn't preserve muscle the way strength training does. Beginner-friendly home sessions with dumbbells are enough to start.
Is it too late to rebuild muscle after losing it?
No. Muscle can be rebuilt at almost any age with progressive strength training and enough protein — women in their 50s, 60s, and beyond do it routinely. Starting now protects the muscle you still have and rebuilds what was lost, whether you're still on the medication or have stopped.
Lose the weight.
Not the muscle.
Skinny Fat Fix is live coached home workouts for women 35+ on a GLP-1 — Mon/Wed/Fri 6:30 AM ET, 30 minutes, form checks, recordings. Your first week is free.
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