The GLP-1 Weight Loss Secret: Why You Need to Protect Your Muscle (and How Functional Fitness Can Help)
Derek Saffold • April 8, 2026
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P.S. If you found this helpful, share it with someone you know who's on one of these medications or is thinking about starting. Most people hear "you're losing weight" and assume everything is working perfectly. Now you know there is more to it and more for you to gain!
Source: Metabolism — Clinical and Experimental, 2025
Let me give you a number: 1 in 8.
GLP-1 medications—like Ozempic, Wegovy, and Mounjaro—are reshaping the conversation about weight loss.
With 1 in 8 American adults reporting use as of 2025, chances are someone you know is experiencing their powerful effects. The truth is, the weight loss is significant, and we’re not here to talk you out of it.
25%. That's the percentage of American adults who, as of 2025, report having used a GLP-1 medication for weight loss. Chances are, someone in your life is on one of these right now. Maybe you are too. And honestly? The results are real.
But we are here to talk about what the research says and ensure your weight loss journey doesn't cost you something invaluable: your muscle and strength. This is the key to lasting results, long-term health, and true functional fitness.
The Study You Need to Know About
A 2025 systematic review in Metabolism analyzed 22 clinical trials to understand exactly how GLP-1 medications affect your body composition.
They found that the drugs work!
On average, people lost 3.55 kg of total body weight.
Here’s the part not getting enough attention: 0.86 kg—roughly 25% of everything lost—came from lean mass.
That includes MUSCLE!
This lean tissue is vital. It keeps your metabolism running, supports your joints, and is strongly correlated with longevity and independence. The more powerful the drug, the worse the muscle loss. In one clinical trial for the potent GLP-1, Semaglutide, nearly 45% of total weight lost came from lean mass.
Losing muscle at this rate is a serious concern for anyone aiming for better health, not just a lower number on the scale.
Why This Muscle Loss Happens
GLP-1 medications work by suppressing your appetite — they make you feel full faster and eat significantly less. That creates a large caloric deficit, which is great for fat loss. However, when calories drop quickly, your body often cuts costs in the easiest place: muscle.
Think of it like a company facing sudden budget cuts. When revenue drops fast, leadership doesn't carefully evaluate every line item — they cut headcount because it's the fastest way to reduce costs. Your body does the same thing with muscle.
Muscle is metabolically expensive to maintain. Without a strong signal telling your body to keep that tissue, it can be burned for fuel. This means you could be losing the very strength and functional capacity you'll need most when the weight loss is complete, and you’re no longer on the medication.
The Solution: Protecting Your Strength with Resistance Training
The good news is that we have the key to sending your body that preservation signal.
Resistance training lets our bodies know that “this tissue is being used” - so do what we can to keep it. Without that, even a clinically proven weight loss drug can end up costing you the very tissue you'll need most when the weight is gone, and you're no longer taking the GLP-1 medication.
What This Means for You
If you are on a GLP-1 medication—or considering one—your focus needs to shift from just the scale to protecting your muscle.
The drug can handle the appetite piece. Your job — and ours — is to protect your muscle
while that's happening.
- Consistent Resistance Training (The Signal). Resistance training is non-negotiable. It tells your body, “This tissue is being used—keep it!” Consistent, challenging training is the most powerful tool you have to mitigate the muscle-wasting effects of a fast caloric deficit.
- Prioritize Protein (The Fuel). Appetite suppression on GLP-1s makes it extremely easy to under-eat, especially protein. Your body needs protein to rebuild and maintain muscle tissue. We recommend setting and hitting high protein targets every single day, even when you don't feel hungry. That's why our training is the Ideal Program for GLP-1 Users
If your goal is to lose fat, we should also be preserving (maybe building some) muscle, strength, and fitness. A comprehensive program like our Pump or Functional Fitness classes is a perfect complement to your GLP-1 journey.
- Resistance Training: Functional Fitness, and Pump incorporates heavy lifting (squats, deadlifts, presses) that provides the powerful signal needed to preserve muscle mass.
- Builds Real-World Fitness: The program is designed around movements that translate into real-world strength and capacity—lifting kids, carrying groceries, moving well for a lifetime.
- Scalable: Whether you’re a beginner or a seasoned athlete, our certified Coaches can scale the intensity to ensure you're challenged enough to protect muscle without over-training.
The scale going down is only part of the story. We want you to lose fat, not the muscle your body needs to stay strong
and functional
for the long haul.
We have the tools and the plan to help you ensure your weight loss results look as good on the inside as they do on the scale, and most importantly, that they stay that way!
Questions about how this applies to your situation specifically? Just send us an email or set up a consultation below!
Meet the Member of the Month for April 2026: Jeremy Clark! What started as a little competitive motivation turned into a full-on commitment to getting stronger, moving better, and showing up consistently.
What is the March of Dimes? The March of Dimes is a non-profit organization dedicated to improving the health of mothers and babies, with a focus on preventing birth defects, premature birth, and infant mortality. Learn more about the March of Dimes here. Why is it important to us? We are excited to host a workout in support of the March of Dimes and the South Shore Hospital NICU team. My sister-in-law, Amanda Dougherty, and my nephew, Owen Dougherty, received a lot of care during Owen's premature and traumatic birth. Amanda and her family will be walking on the SSH NICU/SCN team in the March for Babies walk on May 9th, and we would love to support her by donating to the cause and helping other families in need. When's the charity class? We would love for everyone to come join us, no matter your fitness level, in support of this great cause. The class will be hosted on Sunday, April 12th, at 11 am. T-shirts will also be available for purchase as a preorder up until March 27th. All proceeds from registration of this event and profits from all shirts purchased will be donated to the SSH NICU/SCN team under Amanda Dougherty. Donate and Jump into Class If you would like to donate more, you can go directly to Amanda’s page and donate here.
Strength expression is our ability to show or utilize the strength we have. We call it expression because in the world of lifting, CrossFit, functional fitness, or training, our ability to show that strength varies. Even though our potential strength is the same, we are not always able to fully express it the way we want. Whether that is hitting a max back squat, doing heavy thrusters in a CrossFit style workout, or hitting that heavy clean complex when olympic lifting, we will not always be able to hit our maxes, this is because of factors outside of just our strength itself.
