TRAINING INTELLIGENCE

Ozempic and Muscle Loss: What the Research Actually Says

If you’re losing weight on Ozempic, Wegovy, Mounjaro, or Zepbound, you’ve probably already noticed the scale moving faster than it ever has before.

You’ve also probably seen the headlines about muscle loss. Those are worth understanding properly, because the popular version overstates the problem, and the real version is still a good reason to train.

What the research actually found

The best body composition data comes from an analysis of the STEP 1 trial. Over the study, fat mass fell by around 19 percent and visceral fat by around 27 percent. Lean body mass also fell, by roughly 10 percent.

Here’s the part the headlines leave out. Lean mass as a proportion of bodyweight went up. Participants finished with a better body composition than they started with, not a worse one.

That pattern holds more broadly. Losing lean tissue during substantial weight loss is expected, whether the weight comes off through dieting, surgery, or medication. Systematic reviews haven’t found that these drugs damage muscle beyond what you’d expect from the weight loss itself, and measures of physical function are generally maintained. One 2025 study of people on semaglutide found grip strength improved over a year.

So the framing that the medication is stealing your muscle isn’t accurate. What’s happening is ordinary, and it’s happening faster and on a larger scale than most people have experienced before.

Where the real risk sits

That said, the picture isn’t uniformly reassuring, and it would be dishonest to pretend otherwise.

A 2025 study of older adults with type 2 diabetes found declines in muscle mass, grip strength, and walking speed over two years, with larger doses predicting greater loss. The risk isn’t evenly distributed. It concentrates in people who are older, already carrying less muscle, or losing weight fastest.

And there’s a second issue that has nothing to do with muscle at all.

What happens when you stop

The STEP 1 trial ran an extension that followed people for a year after the medication stopped.

They had lost an average of 17.3 percent of their bodyweight. A year off treatment, they’d regained about two thirds of it. Most of the improvements in blood pressure, cholesterol and blood sugar drifted back toward where they’d started.

That isn’t an argument against the medication. It’s an argument about what else needs to happen while you’re on it. The months you spend losing weight are a window, and what you build during that window is the part that doesn’t leave when the prescription does.

Muscle you’ve built is still there. Strength is still there. Knowing how to eat and train is still there.

Why muscle is worth protecting anyway

Even though the loss is proportionate rather than pathological, it’s still worth minimizing.

Muscle is what holds your joints in position, what gets you up a flight of stairs without your knees complaining, and what decides whether you can get off the floor easily at sixty. If you regain weight later, what comes back is fat rather than the muscle you lost. Go through that cycle twice and you’re worse off at the same bodyweight.

Coming out of this with more muscle than you’d have otherwise isn’t about avoiding a catastrophe. It’s about the difference between smaller and genuinely stronger.

What actually works

A pooled analysis of six trials in older adults with obesity found that resistance training preserved nearly all lean mass during calorie restriction.

Two things produce that, working together.

Lifting gives the signal. Training tells your body the muscle you’ve got is load bearing and in use, which makes it a poor candidate for breakdown while you’re eating less. Cardio is worth doing for other reasons, but it’s meaningfully worse at holding onto muscle during weight loss.

Protein gives the raw material. This is the part these medications make genuinely hard. They work by suppressing appetite, and protein is the most filling thing on the plate. Hitting a protein target when you’re not hungry takes structure, not willpower.

The part nobody warns you about

That’s the tension in the middle of all this. The thing that makes these medications work is the same thing that makes protecting your muscle difficult. You need to eat enough protein at exactly the point where eating has become a chore.

Generic advice falls apart in the face of that. Telling someone to eat more protein is useless when food has stopped being appealing. What works is a structure built around what you can actually get down. Which order you eat things in. Which protein sources go down easily when appetite is low. Front-loading earlier in the day. What to do in the days after an injection when it drops hardest.

Training needs the same treatment. A program written for someone eating plenty doesn’t transfer to someone well under maintenance with less energy to spend.

What it looks like done properly

Resistance training as the main event, not something bolted onto cardio
Loads that progress, so the signal keeps up as you get stronger
A protein target you can realistically hit given your appetite, built around food you can tolerate
Coaching that adjusts as your weight, energy, and appetite shift over the months
Attention to whatever joint issues were limiting you before, because those don’t disappear when the weight does

None of that requires you to be an athlete or to have trained before. Plenty of people who come to us have never lifted seriously, and many arrive with knees, backs, or shoulders they’ve been working around for years.

If you’re weighing up where to do that, we’ve written about what to look for in a place to train while you’re on a GLP-1.

Training on a GLP-1 in Dallas

Using a GLP-1 changes nothing about whether we can work with you. The training and nutrition side is the same work we do with every client, adjusted for reduced appetite and the size of the deficit you’re in. We don’t prescribe these medications and we don’t advise on them. That’s between you and your physician. What we handle is the other half.

Everyone starts with the Transformation and Fitness Strategy Session, a 60 minute in person appointment before training begins. It covers goals, training history, lifestyle, schedule, current ability, and any pain or joint concerns, and it includes a physical assessment. Personalized nutrition coaching is included for every active coaching client rather than sold on the side, which matters more here than usual, because on a GLP-1 the nutrition side is the harder half.

Gryffon Performance is a private training studio in Dallas, TX. 30+ five-star Google reviews. Fifteen thousand square feet, private, built for coaching and nothing else. Every client gets a comprehensive assessment and personalized nutrition coaching, included. We give our clients the coaching and the tools to get results like nobody else in Dallas.

The medication handles your appetite. What you do with these months decides what’s left when it stops.

Apply for coaching and tell us where you’re starting from.

References

Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes, Obesity and Metabolism, 2022;24(8):1553-1564.
Neeland IJ, Linge J, Birkenfeld AL. Changes in lean body mass with GLP-1-based therapies and mitigation strategies. Diabetes, Obesity and Metabolism, 2024.
Sardeli AV, et al. Resistance training and lean mass during caloric restriction in older adults with obesity. Pooled analysis, 2018.