GLP-1 medications are changing how people lose weight. But the muscle loss that comes with them is real — and movement is one of the most important tools for managing it.
What GLP-1 medications actually do to your body composition
Ozempic, Wegovy, Mounjaro, Zepbound, and the other GLP-1 receptor agonists work. The clinical data on weight loss is substantial and consistent. That includes the active ingredients behind these medications: semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), and emerging options like retatrutide. But weight loss on these medications isn’t purely fat loss, and that’s the part that often gets skipped in the conversation.
Studies on semaglutide and tirzepatide consistently show that a significant portion of the weight lost on GLP-1 medications comes from lean mass, muscle tissue, not just fat. Some analyses suggest that 25–40% of total weight lost on these medications is lean mass. In practical terms: for every 10 pounds lost, somewhere between 2.5 and 4 pounds may be muscle.
For someone in their 40s, 50s, or 60s, this matters more than it might for a younger person. We naturally lose muscle mass from our mid-30s onward in a process called sarcopenia. GLP-1 medications, without intentional intervention, can accelerate that loss during a period of life when preserving it is already harder.
The consequences aren’t just aesthetic. Muscle mass is directly tied to metabolic rate, bone density, balance, functional independence, and long-term health outcomes. Losing it faster than necessary while using a medication that’s otherwise working well is a problem worth addressing.
Why exercise is the most important variable
The research here is detailed: progressive resistance exercise is the most effective tool for preserving lean mass during significant weight loss, including weight loss on GLP-1 medications. Not walking. Not yoga. Not low-intensity cardio. Progressive resistance training, movement that challenges your muscles to produce increasing amounts of force over time.
This doesn’t mean you need to become a competitive lifter. It means your exercise program during this period needs to include work that your muscles have to actually adapt to, work that gets progressively harder as you get stronger.
Adequate protein intake is the other major lever. Most GLP-1 users experience significant appetite suppression, which makes it easy to undereat protein even when total calories are well-managed. Protein synthesis is how muscle is built and maintained, and without sufficient dietary protein, resistance training alone can’t fully compensate.
We’re not a nutrition practice, and this isn’t clinical advice. But if you’re on a GLP-1 and working with a doctor or dietitian, asking specifically about protein targets during your weight loss phase is worth doing.
Where reformer pilates fits in
Reformer Pilates isn’t typically thought of as a resistance training modality in the same breath as barbell work or kettlebell circuits. But it does something that conventional resistance training often doesn’t: it builds the foundational body awareness, deep stabilizer strength, and movement quality that make everything else safer and more effective.
Here’s what that means specifically for someone on a GLP-1 medication:
- Reformer Pilates loads the body through spring resistance that is intelligent and adjustable — it builds strength in the hip stabilizers, deep core, and posterior chain in a way that is joint-friendly, even for people who are deconditioned or managing pain
- The proprioceptive demand of reformer work — learning to feel where your body is in space, to control movement rather than power through it — transfers directly to safer, more effective strength training
- The small group, instructor-led format means your movement is being watched and corrected, which matters when you’re building a training foundation during a period of significant physical change
- Many clients on GLP-1 medications experience fatigue, particularly in the early months. Reformer Pilates is adaptable to your energy on a given day in a way that heavy barbell work isn’t — spring resistance can be dialed down without losing the training stimulus
Why pilates alone isn’t enough — and why we built the three-pillar model
We’ve written about this directly: reformer Pilates has a ceiling when it comes to progressive resistance loading. Spring resistance is valuable, but it can’t fully replicate the stimulus that barbell and dumbbell work provide for bone density and maximal strength development.
For clients on GLP-1 medications specifically, this ceiling matters. If preserving lean mass is a priority, and it should be, your program needs to include both.
This is exactly why we built the three-pillar model at Soteria Maitland. Pilates provides the movement foundation. Coached strength training provides the progressive resistance load that Pilates can’t fully replicate. Recovery, structured mobility, breathwork, and programmed deload ensure that the adaptation from both actually sticks.
For clients on GLP-1 medications, this structure is particularly well-suited:
- Pilates sessions establish and maintain movement quality during a period when the body is changing quickly
- Strength sessions provide the progressive resistance stimulus that directly counters lean mass loss
- Recovery sessions address the fatigue and nervous system load that can accumulate when the body is simultaneously managing medication effects and a significant training program
What the research says about Pilates and body composition
Studies on reformer pilates and body composition are more limited than those on conventional resistance training, but the directional evidence is consistent: regular reformer pilates practice improves lean mass retention, functional strength, and musculoskeletal health, particularly in women over 40.
The mechanisms are what you’d expect: reformer pilates engages the slow-twitch stabilizer muscles that conventional training tends to skip, improves intramuscular coordination, and trains movement patterns that transfer to daily function. These aren’t the same adaptations you get from heavy lifting, but they’re complementary to them, which is the point.
If you’re interested in the specific research on GLP-1 medications and lean mass, the sources we’ve found most useful are the clinical analyses from Hinge Health and the work being done at institutions studying semaglutide’s body composition effects. Your prescribing doctor is the right person to discuss your specific situation with.
Who this program is built for at Soteria Maitland
We work with several clients currently on GLP-1 medications, and a larger group of clients who fit the demographic that tends to be prescribed them: women in their 40s, 50s, and 60s who are managing weight, navigating perimenopause or post-menopause, and trying to build a physical practice that supports long-term health rather than short-term aesthetics.
The three-pillar program at our Maitland location was built with this person in mind, not exclusively, but meaningfully. If you are on a GLP-1 and looking for a coached movement program that addresses lean mass preservation directly, the combination of reformer Pilates and progressive strength training we offer is one of the more complete options available locally.
New clients start with an intake conversation. We want to understand your situation — your medication, your goals, your current movement baseline, any physical considerations- before recommending a starting point. From there, your instructor builds a program that fits where you are and where you’re trying to go.
Getting started
If you’re on a GLP-1 medication and want to talk through what a movement program at Soteria could look like for you, reach out directly or book an intake session through the link below. We’re in Maitland, FL, and see clients from across the greater Orlando area.
We don’t have a scripted program for GLP-1 users. What we have is a coaching-forward approach to building the kind of strength that supports whatever else you’re doing for your health.