GLP-1 Medications and Lean Muscle Loss: What You Need to Know By a Sports and Family Medicine Doctor

The Basics: Weight Loss Isn’t Just Fat Loss

When people lose weight—whether through diet, surgery, or medication—they often lose a combination of fat and muscle. Ideally, we want to preserve lean muscle tissue, which plays a crucial role in:

• Metabolism

• Strength and mobility

• Blood sugar regulation

• Long-term weight maintenance

Unfortunately, some early studies suggest that GLP-1 medications may lead to significant muscle loss—sometimes up to 30–40% of total weight lost. That means if someone loses 20 pounds, 6–8 of those pounds might be muscle. This matters, especially for older adults, athletes, or anyone trying to maintain physical performance.

Why Does This Happen?

GLP-1 medications work by suppressing appetite and slowing digestion. While this can help reduce caloric intake and support weight loss, it can also lead to inadequate protein consumption and less spontaneous movement—two key factors that maintain muscle.

Additionally, rapid weight loss in general can promote breakdown of both fat and muscle unless muscle is actively preserved through nutrition and resistance training.

What Can You Do About It?

If you’re using a GLP-1 medication—or considering one—it’s critical to approach your weight loss strategically, with an emphasis on preserving muscle:

1. Prioritize Protein
   Aim for a high-protein diet (generally 1.2–2.0 grams of protein per kilogram of body weight daily, depending on activity level). This gives your muscles the building blocks they need, especially in a calorie deficit.

2. Incorporate Resistance Training
   Strength training at least 2–3 times per week can help prevent muscle loss. Focus on compound movements like squats, rows, and presses that engage multiple muscle groups.

3. Track Body Composition, Not Just Weight
   Tools like DEXA scans or bioimpedance scales can help differentiate between fat and muscle loss, giving a clearer picture of your progress.

4. Stay Active
   Daily movement, even outside of formal exercise—what we call non-exercise activity thermogenesis (NEAT)—helps keep your metabolism up and muscles engaged.

A More Balanced Approach

GLP-1 medications are powerful tools, but they should never be a standalone solution. Used wisely, they can open a door to better metabolic health. But long-term success means protecting your muscle mass, not just watching the scale drop.

As your doctor, my goal is to support your journey in a way that improves your overall health, function, and longevity—not just the number on the scale. If you’re using a GLP-1 medication, let’s make sure you’re also building a plan to stay strong from the inside out.

At Princeton Sports and Family Medicine, P.C., our doctors specialize in sports medicine services, including weight loss, exercise counseling and physician services to assess your risk for injury and assist in your performance goals.

Call or click to book a session with our professionals at Princeton Sports and Family Medicine, P.C. In addition to problem-focused visits, we offer sports performance evaluations to stop problems before they start. Plan your visit today!

Author

Peter Wenger, MD Peter C. Wenger, MD, is an orthopedic and non-operative sports injury specialist at Princeton Sports and Family Medicine, P.C., in Lawrenceville, New Jersey. He is board certified in both family medicine and sports medicine. Dr. Wenger brings a unique approach to sports medicine care with his comprehensive understanding of family medicine, sports medicine, and surgery. As a multisport athlete himself, he understands a patient’s desire to safely return to their sport.