GLP-1 Receptor Agonists and Muscle Mass

In recent years, medications like GLP-1 receptor agonists have revolutionized weight loss treatments, offering new hope to individuals managing obesity and related conditions. These medications, along with other weight-loss strategies, focus on reducing fat mass to improve health outcomes. But as a physical therapist with a whole-health perspective, I urge my patients to ask a critical question: What about muscle?

Muscle is far more than a source of strength. It plays vital roles in metabolism, immune function, and overall well-being. When we lose weight—whether through diet, medications, or surgery—muscle mass can also decrease, which may have long-term consequences for health. Let’s explore why preserving muscle matters and how we can protect it during weight loss.

Why Muscle Matters

Skeletal muscle is more than just "meat on your bones." It’s an active, dynamic tissue that contributes to:

• Movement and Function: Muscle strength supports balance, mobility, and independence, especially as we age.

• Metabolism: Muscle helps regulate blood sugar by absorbing glucose and improving insulin sensitivity, reducing the risk of type 2 diabetes.

• Immunity and Recovery: Muscle provides amino acids for healing, fighting infections, and managing stress.

• Fat Burning: Muscle influences body composition by increasing the number of calories burned at rest.

When we lose muscle during weight loss, we risk compromising these functions. Some studies show that up to 25–40% of weight lost through medications like GLP-1 receptor agonists can come from fat-free mass, including muscle. While the metabolic benefits of losing fat often outweigh the downsides of losing some muscle, we can do better.

The Challenges of Medically Induced Weight Loss

Weight-loss medications like GLP-1 receptor agonists are highly effective in reducing fat mass, but they don’t specifically target fat. This means muscle can also be lost during treatment, especially if we don’t take steps to preserve it.

Even though some research suggests that losing muscle may not immediately impair strength or function, the story doesn’t end there. Long-term loss of muscle mass can increase the risk of frailty, make it harder to maintain weight loss, and decrease quality of life. This is particularly important for older adults, who naturally lose muscle with age.

A Whole-Health Approach to Weight Loss

The good news? You can preserve—and even strengthen—your muscles while achieving weight-loss goals. Here’s how:

1. Focus on Strength Training

• Incorporate resistance exercises like weightlifting, bodyweight movements (e.g., push-ups), or resistance band workouts into your routine.

• Aim for 2–3 sessions per week, focusing on major muscle groups like the legs, back, and core.

2. Prioritize Protein

• Protein is the building block of muscle. During weight loss, aim for about 1.2–1.6 grams of protein per kilogram of body weight daily (consult a dietitian for personalized advice).

• Include high-protein foods like lean meats, eggs, tofu, beans, and dairy in your diet.

3. Stay Active

• Combine strength training with aerobic activities like walking, swimming, or cycling to maintain overall fitness.

• Simple changes, like taking the stairs or walking after meals, add up over time.

4. Work with a Team

• Collaborate with a physical therapist, dietitian, or fitness professional to create a sustainable plan that aligns with your goals and abilities.

• Ask your doctor to monitor your muscle mass and strength during weight-loss treatment to ensure you’re on the right track.

5. Consider New Solutions

• Emerging therapies and medications may help preserve muscle during weight loss. If you’re using medications like GLP-1 receptor agonists, talk to your doctor about combining them with strategies that support muscle health.

The Bigger Picture: Building a Stronger You

Weight loss is about more than the number on the scale. It’s about improving health, mobility, and quality of life. By focusing on muscle strength and function, we can achieve weight-loss goals while maintaining the energy and resilience to enjoy life to the fullest.

Whether you’re using medications, dietary changes, or a combination of approaches, remember that your body is a whole system. Protecting your muscle health isn’t just a fitness goal—it’s a foundation for long-term wellness.

What small steps can you take today to protect your muscles while working toward your weight-loss goals? What support or resources would help you feel stronger and healthier on your journey?