GLP-1 medications such as Ozempic, Wegovy, Mounjaro and Zepbound have changed what weight loss looks like for millions of people. Appetite quiets down, the scale finally moves, and for many of our clients in Herndon and Tysons, it is the first time in years that the number is going the right direction.

Here is the part the prescription label doesn’t tell you: the scale can’t tell the difference between fat and muscle. When you lose weight quickly without strength training, a surprising amount of what disappears is lean mass. That matters for how you look, how you feel, and how well you keep the weight off when the medication stops.

How much muscle do people lose on GLP-1s?

Clinical trials measured it. In the STEP 1 trial of semaglutide (the medication in Ozempic and Wegovy), a subgroup of participants had body-composition scans before and after 68 weeks on the drug. They lost about 15% of their body weight, and lean mass made up roughly 40% of the total weight lost. In the SURMOUNT-1 trial of tirzepatide (Mounjaro and Zepbound), lean mass accounted for roughly a quarter of the weight lost.

Those numbers are similar to what happens with any rapid weight loss from diet alone, so GLP-1s are not uniquely “muscle-wasting.” The problem is that they work so well, so fast, that people lose a lot of total weight in a short time, and a meaningful slice of it is muscle. If you are over 40, you are already losing a few percent of your muscle every decade just from aging. Losing more on top of that is not a trade you want to make.

Why muscle is the part you can’t afford to lose

Muscle is your metabolism. Lean tissue burns calories around the clock. Lose it and your resting metabolic rate drops, which makes maintenance harder and regain more likely.
Muscle protects you when the medication stops. In the STEP 1 extension study, people who stopped semaglutide regained about two-thirds of the weight they had lost within a year. The ones who hold on best are the ones who built habits and kept their strength while on it.
Muscle is how you look “toned,” not just smaller. Fat loss without muscle gives you the “Ozempic face” and loose, soft arms. Muscle gives you shape.
Muscle is your independence. Strength, balance and bone density all depend on it. For anyone 50 and older, muscle is the difference between carrying your own groceries at 80 and not.

The fix is simple, but hard to do while on a GLP-1

Every doctor and researcher says the same two things: eat enough protein and do resistance training two or three times a week.

The protein part is a nutrition conversation for you and your doctor. The resistance-training part is where most people on these medications get stuck, and for understandable reasons:

You have less energy. You are eating far fewer calories, so a 60-to-90-minute gym session can feel impossible.
Nausea and fatigue are real side effects, especially in the first weeks after each dose increase.
Joints hurt. Many people starting a GLP-1 are carrying extra weight on sore knees, hips and backs. Heavy lifting is intimidating or off the table entirely.
You may never have lifted weights before. Walking into a weight room with no plan is a great way to quit by week three.

This is exactly the gap P20 was built to fill.

Why P20’s 20-minute EMS workouts are the perfect match for GLP-1 users

Whole-body muscle activation in 20 minutes. EMS (electrical muscle stimulation) activates far more muscle fibers per movement than a regular workout. In one 20-minute session your EMS suit works your legs, glutes, core, back, chest and arms at the same time while you perform simple exercises with a coach. You get the resistance-training stimulus your body needs to hold on to muscle, without spending hours at the gym on a day when you barely have the appetite for lunch.

No heavy weights, so it is easy on your joints. The resistance comes from the electrical impulses, not from a loaded barbell. That makes EMS a realistic option for people with knee, hip and back pain, and for anyone who has never trained before. Our clients have used it to maintain muscle before surgery and rebuild it afterward when they were not allowed to lift anything heavier than ten pounds. The same gentle, controlled approach works for someone whose body is changing quickly on a GLP-1.

Backed by research in the people who need it most. A randomized trial of whole-body EMS in women 70 and older with sarcopenic obesity (low muscle, high fat) found it increased muscle mass and functional strength, and the researchers described it as a safe and attractive option for people unable or unwilling to do conventional exercise. That is a strong signal for anyone worried about losing muscle during weight loss.

One or two sessions a week is enough. The P20 Method is built around one to two 20-minute sessions per week. That fits the energy budget of someone on a GLP-1 and lines up with the two-to-three-times-weekly resistance training that doctors recommend.

A coach is with you every minute. Your trainer adjusts the intensity of every muscle group in real time. On a low-energy day after a dose increase, we dial it back. On a good week, we turn it up. You never have to figure out a program on your own.

Programs that match where you are in your journey. Start with P20 Strong to protect and build muscle while the weight is coming off. Add P20 HIIT to boost your metabolism and cardio. Move to P20 Power when you are ready to sculpt. Use P20 Recovery on the weeks your body needs a gentle session instead of a hard one.

What a GLP-1 plan at P20 looks like

Book a $35 trial session. You will meet your trainer, get fitted in the EMS suit, and do a full 20-minute workout scaled to your current fitness and energy.
Tell us about your medication. We will plan your sessions around your dosing schedule so you train on your better days, and we will check with you about side effects before every session.
Train once or twice a week and keep your protein up. Most clients notice they feel stronger and more energetic within the first few weeks.
Track more than the scale. We will pay attention to strength, how your clothes fit and how you feel, not just the number.

A quick but important note: talk to your doctor before starting any exercise program, including EMS, and ask about your protein goals while on a GLP-1. EMS is not suitable for people with pacemakers or other implanted electrical devices, heart disease, epilepsy, or who are pregnant.

Ready to protect your muscle while you lose the weight?

You are putting real effort (and real money) into your GLP-1. Don’t let a third of that progress come out of your muscle. Twenty minutes, once or twice a week, is all it takes to keep what matters.

Book your $35 trial session now at P20 Herndon or P20 Tysons, or call or text us and mention this article:

Herndon: 703-559-4040
Tysons: 571-407-1199

We will take it from there.

Sources

Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1), New England Journal of Medicine, 2021. doi.org/10.1056/NEJMoa2032183
Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension, Diabetes, Obesity and Metabolism, 2022. doi.org/10.1111/dom.14725
Look M et al. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study, Diabetes, Obesity and Metabolism, 2025. doi.org/10.1111/dom.16275
Kemmler W et al. Whole-body electromyostimulation to fight sarcopenic obesity in community-dwelling older women, Osteoporosis International, 2016. doi.org/10.1007/s00198-016-3662-z

This article is for general information only and is not medical advice. Ozempic, Wegovy, Mounjaro and Zepbound are trademarks of their respective owners; P20 is not affiliated with them.