By Brad Tillery, Owner & Head Coach, BCS Fitness — College Station & Bryan, TX
Before I get into this, I want to say something directly to those of you on a GLP-1 right now.
You made a decision. You're down weight that wasn't coming off before. That's real, and I'm not going to pretend otherwise or lecture you about it. These medications are legitimate tools, and plenty of people are better off for them.
This isn't a warning. It's a way to make sure the thing you started actually gets you where you want to go.
A conversation that says it all
A client mentioned something to me a couple of weeks ago.
"I'm down 22 pounds since starting the shot… but I feel off for some reason."
I told her she'd seemed like she was dragging a bit lately.
"I'm always dragging now," she said. "I kind of assumed that was part of what I signed up for."
Part of what? "Losing the weight. Food just isn't on my mind anymore."
So I asked how much she was actually eating. "Honestly? Very little. I'm just never hungry."
That's the drug doing exactly what it's supposed to do — it shuts off the food noise. But the body still needs fuel to get through the day, repair muscle, and keep your head clear. Hers wasn't getting enough.
"But I'm losing weight," she said. "Isn't that the point?"
Depends what's coming off.
Key takeaways
GLP-1 medications work by reducing appetite — which can quietly leave you under-eating.
When you don't eat enough, your body burns muscle along with fat. Some research suggests muscle can account for up to 40% of the total weight lost on these medications.
Muscle protects your metabolism, bones, balance, and independence — especially after 40.
You don't have to stop the medication or force-feed yourself. You just have to protect the muscle with two things: protein and strength training.
Protein floor: roughly 100g/day for an average-built woman, 150g/day for an average-built man.
Do GLP-1 medications cause muscle loss?
They can — not because the medication is "bad," but because of how most people end up eating on it.
Some of the weight you lose is fat. Some of it is muscle. And on these medications, it can be a lot more muscle than people expect. Some research puts it as high as 40% of total weight lost. When you're barely eating, your body simply isn't getting what it needs to hold onto lean tissue.
Why would your body burn muscle when you have fat to spare?
Because your body doesn't care what looks good on you. When fuel doesn't show up, it goes into survival mode and breaks down whatever it can use — and muscle is easy to use.
Here's what makes this especially important after 40: you're already losing a little muscle every year just from aging. Not eating enough protein on top of that accelerates something that's genuinely hard to get back.
So is the shot working against you? No. The shot is working fine. It's the plate that isn't keeping up.
How do you keep muscle while losing fat on a GLP-1?
Here's the encouraging part: this is a completely solvable problem.
You don't have to stop the medication. You don't have to force yourself to eat tons of food you have no appetite for. You don't have to undo anything. You just have to protect the muscle while the fat comes off — and the two things that do that are things you may already be set up for.
1. Protein. Not more food overall — more protein inside the food you do eat. When your appetite is low, every bite has to work harder, so make it count.
2. Strength training. Lifting tells your body, "keep this muscle, we're still using it." That signal matters more right now than it ever has. Two focused strength sessions a week is enough to send it.
People on a GLP-1 who are also strength training and getting their protein in are in a genuinely great position: losing fat while keeping the muscle that protects their metabolism, bones, balance, and independence.
How much protein do you need on a GLP-1?
As a floor — not a ceiling — aim for roughly:
~100g per day for an average-built woman
~150g per day for an average-built man
That's the version of this that works. And if you're already strength training, you're halfway there just by showing up.
Your right-now action step
Pick ONE meal today where you'll eat protein even though you don't feel hungry for it. Eggs. Chicken. Greek yogurt. A protein shake if chewing feels like too much. Just one meal.
That's it. Start there and build.
Let's figure out your numbers
If you're on a GLP-1, come talk to me or one of your coaches. This is worth a real conversation, not a guess — we'll help you figure out what your protein and training should actually look like for your body and your goals. (And always keep your prescribing physician in the loop — we work alongside your medical care, not in place of it.)
You're not doing this wrong. You just need the plate to catch up.
Frequently asked questions
Does weight loss on a GLP-1 cause muscle loss? It can. When appetite drops and you under-eat, the body breaks down muscle as well as fat. Some research suggests muscle may account for up to 40% of total weight lost on these medications. Adequate protein and strength training sharply reduce that muscle loss.
How much protein should I eat on a GLP-1? As a general floor, aim for about 100g of protein per day for an average-built woman and about 150g per day for an average-built man. Focus on getting protein into the food you already eat rather than eating more food overall.
Do I have to stop my medication to keep muscle? No. You don't have to stop the medication or force-feed yourself. Protecting muscle is about prioritizing protein and strength training while the medication does its job.
Why does muscle matter so much after 40? Muscle protects your metabolism, bone density, balance, and independence — and you naturally lose some each year as you age. Keeping it is one of the most valuable things you can do for long-term health.
About the author
Brad Tillery is the owner and head coach of BCS Fitness, a strength and personal-training studio serving College Station and Bryan, Texas since 2003. BCS specializes in prescriptive, coach-led training for busy adults 40 and over, including members pursuing fat loss while on GLP-1 medications.
BCS Fitness South Studio: 3032 Barron Rd, Suite 100, College Station, TX 77845 Central Studio: 4301 Texas Ave, Suite 100, Bryan, TX 77802 Phone: 979-575-7871 · Web: bcsfitness.com
This article is educational and not medical advice. Always consult your prescribing physician before making changes related to your medication, nutrition, or exercise.
