If you are taking a GLP-1 medication like Ozempic, Wegovy, or Zepbound, there is a question worth asking beyond what the scale says.
Are you losing muscle along with weight?
The short answer is: probably yes. And that is completely normal.
If you examine the entirety of the scientific evidence on weight loss, you see a long history of muscle loss when losing weight. Even with aggressive strength training and high protein intake, individuals losing large amounts of weight will lose 10-20% of their total weight loss from muscle tissue. The greater the weight loss, the greater the loss of muscle mass. This happens whether you use medication or not.
So if muscle loss is inevitable, what actually matters?
The Real Question: Is Your Muscle Still Working?
Losing some muscle mass during weight loss is expected. But Losing muscle function is not inevitable. That distinction changes everything.
Muscle mass is the total amount of muscle tissue in your body. Muscle function is what your muscles can actually do. These are two different things, and the difference matters more than most people realize.
Your muscles produce force at low speed, or what we call this strength, and we use it when lifting something heavy. Your muscles produce force at higher speed which we call power, and we use it every time we get up from a chair. Your muscles also sustain effort over time without fatigue. That’s called endurance, and we use it carrying groceries in from the car.
Here is what the research shows: muscle function can improve significantly even when muscle mass decreases. Strength and power improvements have a lot to do with the signals your brain sends to your muscles through the spinal cord. Those neural pathways can be strengthened through resistance training, resulting in real gains in strength and power with little or no change in muscle mass.
This is not theoretical. At AFS, we see this in our own member outcomes. Members on anti-obesity medications who are losing significant amounts of weight and muscle mass still show increases in upper and lower body strength, power, and endurance. We observe this trend regardless of age, gender, or experience level.
Why “Preventing Muscle Loss” Misses the Point
Some skeptics will say that muscle loss on GLP-1s is a disqualifying side effect. That skepticism is unfounded, because it conflates muscle mass with muscle function.
If you are not training to be a professional bodybuilder, muscle mass is not your primary concern. You want to get to a healthy body weight, move around like you used to, and take back control of your health. You want to play with your kids or grandkids, go up and down stairs without pain, and have fewer aches and pains.
Those outcomes come from improved muscle function, independent of muscle mass.
Research published in the New England Journal of Medicine has documented body composition changes during GLP-1 use:
- https://www.nejm.org/doi/full/10.1056/NEJMoa2032183
- https://www.nejm.org/doi/full/10.1056/NEJMoa2206038
Additional studies in JAMA and JAMA Network Open confirm that fat-free mass reductions occur during rapid weight loss:
- https://jamanetwork.com/journals/jama/fullarticle/2777886
- https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2799209
But the functional outcomes depend on what you do alongside the medication.
How to Improve Muscle Function on a GLP-1
A well-designed, progressive strength training program should be your focus. Even doing as little as 1-2 days per week of strength training with one set for all the major muscle groups can be enough to improve muscle function significantly.
Effective programs prioritize multi-joint exercises that load large muscle groups. Movements like squats, rows, and presses train the body to produce force across multiple joints at once, which is how the body actually moves in real life.
Incorporating power training improves the speed at which muscles can generate force. This becomes more important with age, since power declines faster than strength.
Building endurance with moderate-intensity resistance work improves how long muscles can sustain effort. This supports stamina for everyday activities without early fatigue.
Progressive overload—gradually increasing the challenge over time—keeps the body adapting. Adequate recovery is particularly important during a calorie deficit, when the body needs more time to repair.
What This Means for Long-Term Results
Many people worry about what happens when they stop or reduce a GLP-1 medication. That concern is valid if you have lost muscle function along with mass.
But if you have maintained or improved your strength, power, and endurance during weight loss, your body is better equipped to stay active after the medication changes. That ongoing activity supports continued metabolic health and weight maintenance.
The goal is not to “prevent” muscle loss because some loss is normal and expected. The goal is to protect and improve what your muscles can do
Who Should Pay Closest Attention
- People losing weight quickly
- Those using lower doses or micro-dosing over longer periods
- Individuals over 40 who already face age-related declines in muscle function
- Anyone planning to taper or discontinue medication in the future
The AFS Approach
At AFS, we take a strength-first, prevention-oriented approach. We focus on protecting muscle function not just chasing a number on the scale or worrying about tissue loss that is going to happen anyway.
Programs are built around structured resistance training, accountability, and progression matched to where your body is today. Our Exercise Physiologists design programs for people on GLP-1s, and we track both body composition and functional outcomes.
Whether you are currently on a GLP-1, using a small dose, or preparing for life after medication, the goal is the same: improve how your body works, not just how much it weighs.
