Ozempic Muscle Loss Over 40: Why It Happens and How to Stop It

If you’re on Ozempic, Mounjaro, or Wegovy and the number on the scale is dropping but you don’t feel any stronger — you’re not imagining it.

I’ve had more and more clients come to me over the past year in exactly this spot. They’re delighted the weight’s coming off, but something feels off. Clothes are looser, sure, but they’re weaker in the gym, more tired, and honestly don’t look how they expected to look at this new weight.

Here’s what’s actually going on.

The bit nobody tells you about GLP-1s

Ozempic and the other GLP-1 medications are brilliant at what they’re designed to do — they switch off your appetite and the weight comes off. But your body doesn’t know the difference between “good” weight and “bad” weight when it’s short on calories. It’ll happily burn muscle right alongside fat if you give it no reason to hang on to that muscle.

And after 40, this matters more than it would have at 25. You’re already losing muscle naturally with age, and that process speeds up through your 40s and 50s. Add a GLP-1 medication with no strength training or protein plan behind it, and you can end up losing a genuinely significant chunk of muscle along with the fat. For some people, muscle makes up a large share of everything they lose.

That’s how you end up “skinny fat” — a lower number on the scale, but a softer, weaker body than the one you were hoping for.

Why this is fixable — and pretty easily

The good news: this isn’t inevitable. It’s just under-managed. Muscle is maintained through use — your body only holds on to what it thinks it needs. Give it a reason to keep it (proper strength training) and the fuel to keep it (enough protein), and you can lose the fat while protecting, and in a lot of cases actually improving, your strength and shape.

This is exactly the gap I sit in with a lot of my clients right now. The GLP-1 handles appetite. I handle making sure what you lose is fat, not the muscle you’ll want for the next 40 years.

What actually needs to happen

Strength train, properly, 2–3 times a week. Not classes, not random cardio — resistance training that challenges your muscles enough to send the “keep this” signal. Compound lifts (squats, presses, rows, deadlift variations) give you the most return.

Get your protein in. This is the piece almost everyone on a GLP-1 gets wrong, because appetite suppression makes it hard to eat enough of anything, protein included. You need considerably more than you think, spread across the day.

Don’t chase the scale too hard. Rapid weight loss pulls more muscle with it. Slower and steadier, backed by training, protects more of what you want to keep.

Get your recovery right. Sleep and hydration matter more here than people realise — especially once you’re eating less overall.

Why this matters more than the number on the scale

In ten or twenty years, the number that matters isn’t what you weighed in 2026. It’s whether you can still carry your shopping, get up off the floor easily, and keep up with your kids or grandkids without your body holding you back. Muscle is what protects all of that. It’s also what keeps your metabolism working for you instead of against you.

If you’re on a GLP-1 and doing this alone, you’re leaving a lot of that protection on the table.

Where I come in

This is exactly what The 40+ Reset is built for — an 8-week training and nutrition programme designed for people over 40, whether you’re on a GLP-1 or not, that makes sure the weight you lose is fat, and the strength you build actually sticks.

If you’re on Ozempic, Mounjaro, or thinking about starting one, and want to do it properly — get in touch. I train out of UNTIL in Soho and Marylebone, and online too if London’s not doable.