Weight loss injections like Wegovy® and Mounjaro® are changing lives. Originally made to help manage type 2 diabetes, these medications now help people shed large amounts of weight—often more than 10% of their total body weight.
For many people, they’ve been a game-changer: less hunger, smaller portions, and better energy. They’re helping people feel more in control of their health, and that’s something to celebrate.
But as physiotherapists who work with people’s muscles, joints, and movement every day, we want to share an important message that often gets missed.
You Might Be Losing More Than Just Fat
These injections are very effective—but studies show that a big chunk of the weight lost might come from muscle, not just fat.
In some people, up to 4 out of every 10 pounds lost may be from muscle and bone rather than fat [1].
Why does this matter?
Because muscle is vital—not just for lifting weights or looking toned, but for balance, energy, mobility, and even your metabolism.
Why Muscle Matters More Than You Think
Muscle keeps us upright. It helps us move confidently, climb stairs, lift shopping bags, and catch ourselves if we trip. As we get older, muscle also helps protect us from:
- Falls and broken bones
- Slowing metabolism
- Fatigue and frailty
- Losing independence
In fact, muscle is the most active tissue in your body, helping to control blood sugar, support bones, and burn calories—even when you’re resting [2,3].
When we lose too much muscle during weight loss, we can feel weaker, more tired, and increase our risk of injury. That’s why how you lose weight is just as important as how much.
Why It Happens with Injections
GLP-1-based weight loss medications work by reducing your appetite—sometimes dramatically. That means you’re likely eating less, but also potentially getting less protein and not using your muscles as much, which leads to muscle loss.
The good news? You can do something about it.
How to Keep Your Strength While Losing Weight
Research shows that people who add resistance training—things like bodyweight exercises or lifting weights—while using weight loss injections lose much less muscle than those who don’t [4].
In one study, people who combined exercise with the injection kept nearly 40% more muscle than those who used the medication alone.
That’s a big difference in strength, balance, and long-term health.
What We Can Do to Help
At Great Northern Physiotherapy, we help people stay strong and active while losing weight. Using our specialist equipment, we can:
✅ Measure how strong your muscles are with our K-Force strength tests
✅ Use ultrasound imaging to see the quality and size of your muscles (yes, we can see inside!)
✅ Help you build a safe, effective plan to keep or improve your strength while you’re losing weight
✅ Support you to move better, feel stronger, and protect yourself from injury or frailty
Even if you’re not noticing muscle loss yet, these changes can happen quietly over time. That’s why getting a baseline now—and tracking your progress—is so important.
Who Is This For?
You might benefit from a Muscle Health Check if:
- You’re using or starting Wegovy®, Mounjaro®, or similar weight loss injections
- You’re losing weight quickly
- You’re over 50 or want to stay active for years to come
- You’ve had falls, joint pain, or feel weaker than usual
- You just want to understand your real body composition, not just your weight
Book Your Muscle & Movement Health Check Today
Weight loss is a fantastic step toward better health—but don’t let strength be the cost.
Let us help you stay strong, safe, and confident in your body—through weight loss and beyond.
References
- Dubin, R. L., Heymsfield, S. B., Ravussin, E., & Greenway, F. L. (2024). Glucagon‐like peptide‐1 receptor agonist‐based agents and weight loss composition: Filling the gaps. Diabetes, Obesity and Metabolism, 26(12), 5503-5518.
- Cava, E., Yeat, N. C., & Mittendorfer, B. (2017). Preserving healthy muscle during weight loss. Advances in nutrition, 8(3), 511-519.
- Wolfe, R. R. (2006). The underappreciated role of muscle in health and disease. The American journal of clinical nutrition, 84(3), 475-482.
- Lundgren, J. R., Janus, C., Jensen, S. B., Juhl, C. R., Olsen, L. M., Christensen, R. M., … & Torekov, S. S. (2021). Healthy weight loss maintenance with exercise, liraglutide, or both combined. New England Journal of Medicine, 384(18), 1719-1730.
