GLP-1 Medications and Your Clients

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With the rise of medications like Ozempic®, Wegovy®, and Mounjaro®, GLP-1 receptor agonists have become a popular—and often highly effective—tool for weight loss. But with fast body composition changes come new questions about muscle maintenance, exercise performance, and safe, sustainable fitness routines.

As a fitness professional, it’s essential to understand how these medications work, what their impact is on your clients’ physical performance, and how to support them in staying strong and functional throughout their journey. Here’s what you—and your clients—need to know.

What Are GLP-1 Drugs and How Do They Work?

GLP-1 stands for glucagon-like peptide-1, a naturally occurring hormone that helps regulate blood sugar levels and appetite. GLP-1 receptor agonist medications mimic this hormone, enhancing its effects. Originally developed to treat Type 2 diabetes, they are now widely used for medical weight loss due to their ability to:

• Slow gastric emptying (helping clients feel fuller longer)
• Decrease appetite and food cravings
• Promote insulin secretion and glucose control

Common GLP-1 medications include:

• Semaglutide (Ozempic®, Wegovy®)
• Tirzepatide (Mounjaro®), which also mimics GIP (glucose-dependent insulinotropic polypeptide)

“These medications help regulate blood glucose and reduce appetite, often resulting in significant weight loss in people with obesity or Type 2 diabetes” (American Diabetes Association, 2024).

The Muscle Mass Trade-Off: What the Science Says

Rapid weight loss often means both fat and muscle are lost. Clinical studies show that up to 30–40% of the weight lost with GLP-1 drugs can come from lean body mass, including muscle tissue (Lundgren et al., 2021).

That’s a big concern—especially for aging adults who are already at risk of sarcopenia (age-related muscle loss). Muscle is not just for aesthetics or strength; it plays a critical role in metabolism, balance, insulin sensitivity, and mobility.

Clients on GLP-1 medications who are not actively strength training or consuming adequate protein are at higher risk of muscle loss, which may:

• Slow metabolism
• Increase injury risk
• Reduce physical performance
• Undermine long-term weight maintenance

“Loss of lean body mass during rapid weight reduction is a known phenomenon and requires strategic exercise and nutrition interventions” (American College of Sports Medicine, 2023).

Fitness and Strength Training: Essential for GLP-1 Users

The best defense against muscle loss is a strong resistance training and protein-focused nutrition program. Clients using GLP-1 drugs should be coached to:

1. Lift weights 2–4 times per week
   Focus on full-body strength training that includes compound lifts (like squats, rows, and presses) and bodyweight exercises (like planks or push-ups). Emphasize progressive overload.
2. Incorporate functional movement
   Include balance, mobility, and core strength exercises to support daily function and prevent injury.
3. Consume adequate protein
   A registered dietitian or medical provider should help determine needs, but general guidelines recommend 1.2–2.0 grams of protein per kg of body weight, especially when aiming to preserve muscle during weight loss.
4. Prioritize recovery
   Clients on GLP-1s may experience low energy, dehydration, or nausea. Modify workouts as needed, and monitor how clients respond to training loads.
5. Progress slowly
   Significant weight loss can change joint alignment, movement mechanics, and cardiovascular response. Be mindful of form and avoid overloading too quickly.

What to Ask Your Clients Using GLP-1 Drugs

As a fitness professional, you are not prescribing medication—but you can play a powerful role in helping clients exercise safely and maintain muscle and function. Ask questions like:

• What medication are you taking, and for how long?
  Knowing whether they are on semaglutide, tirzepatide, or another medication helps frame your approach.
• Have you experienced any side effects, such as fatigue, dizziness, or nausea during workouts?
  GLP-1 drugs may reduce food intake so significantly that clients don’t fuel properly, which can impact performance and safety.
• Are you working with a registered dietitian or healthcare provider?
  Collaborate when possible to support a well-rounded care team.
• Have you noticed strength changes, balance issues, or increased soreness?
  This may indicate muscle loss or under-recovery and could be a sign to scale back or adapt programming.
• Are you comfortable discussing your goals beyond weight loss?
  Shift the focus toward performance, function, and strength, which builds confidence and long-term sustainability.

“The fitness professional’s role in client education, motivation, and adaptation is vital when medical interventions are part of a client’s health journey” (National Academy of Sports Medicine, 2024).

Empowering Clients Beyond the Scale

GLP-1 medications offer a powerful tool for individuals struggling with obesity and metabolic health, but they are not a substitute for exercise and healthy lifestyle habits. Fitness professionals have an opportunity—and a responsibility—to support clients in preserving muscle, improving function, and feeling strong and empowered as they navigate this journey.

With the right program, education, and support, clients can use GLP-1 medications as a launchpad for sustainable change, not a shortcut with unintended consequences.