Most people are excited to start losing weight on GLP-1 drugs such as Ozempic, Wegovy, and Mounjaro - until they realize that it’s not only fat melting away. GLP-1 muscle loss is incredibly common, and it takes a toll on how you look and feel.
So why does GLP-1 cause muscle loss? There are actually a few reasons. The first and most obvious is you’re consuming fewer calories, and your body turns to its own internal stores (fat and muscle) for fuel in the face of a deficit. But changes in energy expenditure, along with hormonal and metabolic shifts, play a part as well.
Don’t worry, we’ll show you how to avoid muscle loss on GLP-1 drugs in this guide - at least, as much as possible. Some atrophy is all but inevitable when you’re dealing with the type of rapid weight loss these drugs are known for producing.
What Are GLP-1 Drugs?
GLP-1 drugs were originally a medication for managing diabetes, but today, they’re more popular for their connection to weight management. These medications mimic a natural hormone in your body called glucagon-like peptide-1 - better known as GLP-1.
That hormone plays a big role in controlling blood sugar and appetite. It tells your brain you’re full, even if you’re not. It also slows how quickly your stomach empties and helps your pancreas release insulin after meals.
Whether it’s Byetta vs Ozempic, Zepbound, Wegovy, or Mounjaro, there are quite a few different brand names - and while each works a little differently, the end result is more or less the same. That’s to say, the benefits and the side effects are closely related across this class of drugs.
While you hear all about the rapid weight loss, you probably know people also experience complications such as GLP-1 constipation, fatigue, nausea, and more. But what about GLP-1 muscle loss?
Why Does GLP-1 Cause Muscle Loss?
So, does GLP-1 cause muscle loss? Unfortunately, this is pretty common. These medications suppress appetite and slow digestion so well that people often lose not just fat, but also lean muscle mass.
While you’re not guaranteed to experience GLP-1 muscle loss, we’ve seen studies reference that anywhere from 25-40% of total weight lost on GLP-1 drugs can come from lean tissue.
That’s definitely not ideal when muscle is what drives your metabolism, supports mobility, and stabilizes blood sugar long-term. So, why does GLP-1 cause muscle loss?
Reduced Caloric and Protein Intake
GLP-1 drugs blunt hunger, which sounds great until you realize that leaves you in a place where you’re not eating enough to support muscle maintenance. The body starts breaking down muscle tissue to meet its energy needs when calories and protein dip too low for too long.
Protein is also the main building block of muscle, so it’s really easy to slip into a protein deficit if your diet only includes a few bites of food per meal. That deficit makes it harder for muscles to repair after daily movement or exercise, which leads to a gradual loss in strength over time.
Small, nutrient-dense meals with complete proteins (chicken, eggs, Greek yogurt, lentils, tofu) throughout the day can help offset this risk, but people on GLP-1 have a hard time eating that frequently or eating enough due to nausea or early fullness.
Changes in Energy Expenditure
Your resting metabolic rate (RMR) naturally declines as body weight drops. That means you burn fewer calories at rest. Unfortunately, RMR plummets faster when muscle mass decreases since muscle tissue burns more calories than fat does.
This creates a vicious cycle: less muscle → lower metabolism → less energy → more muscle breakdown. It’s also why some people experience a plateau or regain weight after stopping the drug. Their metabolism is now running on a smaller “engine.”
You can disrupt this cycle through resistance training, as we’ll talk about in a moment when we get into how to avoid muscle loss on GLP-1 drugs.
Hormonal and Metabolic Shifts
GLP-1 drugs influence more than appetite. They also alter insulin, glucagon, and growth hormone pathways that regulate how your body uses and stores energy.
Being in a calorie deficit for a long time can decrease levels of anabolic hormones like IGF-1 and testosterone. Both of these are essential for maintaining lean muscle mass. Meanwhile, cortisol (the stress hormone) skyrockets during rapid weight loss, making matters even worse.
Older adults, post-menopausal women, and anyone who’s already deconditioned are particularly at risk because they start with less muscle mass and have a harder time rebuilding it. But that doesn’t mean GLP-1 muscle loss is inevitable.
Can You Build Muscle While on GLP-1 Medications?
Building muscle while taking a GLP-1 drug isn’t impossible - just way harder. The main challenge is that these medications make eating enough nearly impossible for some people.
GLP-1 drugs dull hunger cues, slow digestion, and reduce calorie intake so much that your body often doesn’t get the raw materials it needs to build or repair muscle tissue. Progress can stall when nutrition is limited, even with exercise.
Your metabolism shifts toward conservation mode when you’re on a GLP-1. Your body is trying to hold onto what it has, so actually building muscle is a bit of a stretch. The goal turns to figuring out how to avoid muscle loss on GLP-1 drugs as much as possible.
How to Avoid Muscle Loss on GLP-1 Drugs
Avoiding muscle loss while using a GLP-1 drug is certainly an uphill battle, but there are things you can do to preserve lean muscle mass as much as possible. Let’s start with the obvious defense against GLP-1 muscle loss: protein!
Protein, Protein, Protein!
Muscle tissue breaks down and rebuilds constantly - and protein is responsible for fueling this process. You have to make a concerted effort to eat enough protein on GLP-1s since appetite often drops below what’s needed to maintain that cycle.
Most people do best aiming for 0.8-1.2 grams of protein per pound of body weight on a daily basis. So if you weigh 150 pounds, you should target 120-180 grams of protein every day. Split that evenly across 3-4 meals or snacks to keep muscle protein synthesis active all day long.
We know full meals can be tough to finish, so turn to easier options: Greek yogurt, whey isolate shakes, collagen with added leucine, or small servings of lean fish or eggs. What matters most is hitting your target consistently, not eating “big” meals occasionally.
Don’t Overlook Micronutrients
Even mild deficiencies can stall recovery. Magnesium supports energy production inside muscle cells; vitamin D regulates muscle function and hormonal balance; B12 and iron carry oxygen to tissues.
But micronutrient gaps show up fast since people on GLP-1s often eat less variety. It’s worth running a basic nutrient panel every few months to see for sure what you’re missing out on. Then, address what’s low through food first (leafy greens, fatty fish, legumes), supplements second. You can learn more about vitamins for gut health in our blog.
Integrate Resistance and Mobility Training
You don’t need to become a bodybuilder or powerlifter, but you do need consistency. Two to three strength sessions a week are all it takes to maintain lean muscle mass. Even 20-minute routines using resistance bands or bodyweight is better than nothing!
That said, we encourage you to focus on compound movements such as squats, bench, overhead press, and deadlifts. You can round out your training with secondary movements like flys, lunges, rows, and more.
Mobility work matters too. Range of motion and stability tend to degrade with muscle tissue. Combine resistance training with light mobility drills (like hip openers or shoulder rotations) to keep your body functional.
Support the Gut-Muscle Axis
Gut health directly influences how well your body absorbs protein, minerals, and amino acids. An inflamed or imbalanced gut is much less likely to be capable of absorbing all the nutrients you need to avoid GLP-1 muscle loss.
So, nurture the gut as much as you can with balanced fiber intake, fermented foods, or targeted postbiotics. resM™ GLP-1 Postbiotic is an excellent choice. It has a heat-inactivated probiotic, Chromium, White Mulberry, Fenugreek, and Vitamins D3 & Vitamin B12.
Hydration, Sleep, and Stress Control
Muscle repair happens at rest, not during workouts. That’s why we can’t stress enough the importance of quality sleep every night when trying to prevent GLP-1 muscle loss. Poor sleep decreases growth hormone and IGF-1, both essential for muscle preservation. Get 7-9 hours every night.
Hydration is equally practical. Even mild dehydration can reduce muscle performance and slow nutrient transport. Sip water steadily through the day instead of chugging at night.
You also need to have healthy coping mechanisms for stress. Like we said earlier, stress can lead to heightened cortisol levels in the body, which only makes muscle breakdown worse. A post-meal walk, journaling, or deep breathing can keep that response in check.
Exploring Other Healthy Weight Management Strategies
This likely goes without saying, but the best way to avoid GLP-1 muscle loss is to not use these types of medications in the first place. You should have a serious conversation with yourself about what matters more to you - weight loss or muscle preservation.
The truth is, there are plenty of semaglutide natural alternatives worth exploring if you’d rather not suppress appetite so aggressively or interfere with muscle metabolism.
Start with a simple caloric deficit. You don’t have to cut 500+ calories a day. Even a deficit of 200-300 calories per day will slowly but surely melt away fat, as long as you’re consistent. You can pair a healthy diet with exercise to push the deficit even further and support metabolism.
Remember the role of gut health, too. A balanced microbiome supports better digestion, nutrient absorption, and inflammation control, all linked to healthy weight management. Some people find that their energy improves and healthy weight regulation becomes easier when their gut is functioning optimally.*
This is why we want to once again encourage you to learn about the science supporting resM as part of your healthy weight management regimen. It can help quiet the food noise so you can reach your goals naturally.*
Parting Thoughts on GLP-1 Muscle Loss
GLP-1 drugs can drive impressive weight loss, but at what cost? For many, it’s muscle atrophy. So why does GLP-1 cause muscle loss? It all comes down to caloric deficit, nutrient deficiency, hormone changes, and stress.
The good news is you now know how to avoid muscle loss on GLP-1 drugs. Fuel your body well, train with purpose, and maintain gut health so your metabolism stays active and resilient.
Want to learn more about GLP-1 drugs? Our blog has resources such as Tirzepatide vs Ozempic, how to qualify for GLP-1, and many more. The only thing left to do at this point, though, is learn about the science behind our GLP-1 probiotic - resM.
Build from the inside out. Discover how resM supports gut and metabolic health today.*