How to protect your muscle on a GLP-1

When you say you’re taking a GLP-1 medication to help you lose weight, you might want to be more specific. What most people are hoping to drop is extra body fat — not so much any other healthy body parts. 

“Successful weight loss is not really about weight loss as much as it is about building a healthier, more functional body,” says Dr. Yen-Yi Juo, M.D., a bariatric surgeon and obesity medicine physician at Legacy Good Samaritan Medical Center in Portland, Oregon. “A major part of that is preserving muscle, because muscle helps us stay strong, lets us move our bodies the way we want to, and helps us burn off more energy.” 

Any time you shed pounds, some of that weight comes from fat and some from lean mass, which includes muscle, bone, and other tissue. So some muscle loss when taking a GLP-1 is expected. But there are steps you can take to give your body a better chance of holding onto muscle as the number on the scale goes down. Here’s why that’s so important — and how to do it.

Key takeaways

• Some lean mass is lost during weight loss, including weight loss with GLP-1 medications. 

• Losing weight very quickly and eating too little overall can result in more muscle loss.

• Doing resistance training and getting enough protein can help preserve muscle during weight loss.

If you’re losing weight on a GLP-1 medication, you may lose some muscle in the process, but it’s not exactly caused by the medication per se. “There's nothing metabolically unique about GLP-1s making them target skeletal muscle,” says Dr. Edwin Davila, D.O., an internal medicine physician, clinical exercise physiologist, certified sports nutritionist, and National Academy of Sports Medicine advisory board member. In fact, GLP-1 medications don’t cause more muscle loss than losing weight with lifestyle changes alone. A 2026 meta-analysis of 20 randomized controlled trials found that about 25% to 39% of the pounds shed by participants taking a GLP-1 came from lean mass (which includes muscle, as well as bone, water, organs, and other tissues) — a proportion roughly similar to those who lost weight without a GLP-1. 

Whenever you lose weight by any method, you lose a combination of fat mass and lean mass. And that’s true for the pounds you lose with the help of a GLP-1 too. “GLP-1 medications promote weight loss by reducing appetite and food intake, which creates a calorie deficit, meaning the body is receiving less energy from food than it needs,” says Juo. “When that happens, the body looks for stored energy sources and may break down both fat and muscle in order to extract energy to make up for the deficit.”

Muscle helps you do just about everything from climbing stairs and carrying groceries to simply getting up from a chair to walk your dog or play with your kids. Muscle is also metabolically active tissue and burns nearly three times as much energy (i.e. calories) at rest as fat tissue does, so maintaining it may help support both physical function and a healthy metabolism as your weight changes. This becomes increasingly important as you age, when muscle mass and strength naturally decline. 

What’s more, researchers increasingly view skeletal muscle as an organ that communicates with the rest of the body, including the brain. Muscle releases signaling molecules called myokines that may influence processes involved in brain health, including inflammation, cognition, sleep, and mood. The science is still evolving, but it's another reason preserving muscle during weight loss is important for more than just a toned physique.

Research suggests anywhere from about a quarter to just under half of the weight lost with a GLP-1 may be lean mass. The exact percentage varies by study and by medication: In a 2026 International Journal of Obesity meta-analysis, lean mass accounted for approximately 26% of total weight loss on tirzepatide (the active ingredient in Zepbound and Mounjaro) and up to 45% on semaglutide (the active ingredient in Wegovy and Ozempic). So, for example, if you dropped 30 pounds on Zepbound, you could expect about 22 pounds of that to be fat, and the rest to come from lean mass (including muscle, bone, water, and other tissue). Note the real upside there: On the whole, because GLP-1 medications cause even more fat loss, the net result is still a substantial improvement in body composition.

That said, what you do while taking a GLP-1 still matters in terms of preserving as much muscle as possible. “Faster weight loss often means the body is experiencing a larger energy deficit, meaning it is receiving much less energy from food than it needs,” says Juo. “Some people may unintentionally eat too little protein or too few calories overall, which can increase the chance of losing muscle.”

#1 Prioritize protein

Protein makes up a good portion of our muscle tissue, but that’s not all it’s good for. Protein is used throughout the body to make all kinds of new cells, hormones, signaling molecules, antibodies, and other things. Yet, interestingly, it’s the only macronutrient the body doesn’t store in abundance, notes Davila. 

“We store sugar in the form of glycogen, and we store fat inside of adipose cells, so if we need it later, it’s there. But there's no storage for protein,” he says. “And so when you’re not consuming enough protein to do all of these very important life-maintaining things, the body is going to look for a reserve, break it down, and use its building blocks to do other stuff — and it does that by stripping muscle.”

That’s why it’s crucial to understand how much protein you need and try to hit that goal even as you’re eating less food overall. Weight Watchers recommends that members on a GLP-1 aim for at least 1 gram of protein per kilogram of current body weight. You could try and do that math as the scale goes down, or you could just use the WW app. It calculates your protein goal for you, and every time you track a meal, it updates your daily progress towards that protein goal (and towards other nutrient goals including fiber). 

While you can find just about any food fortified with protein these days, from pudding to potato chips, stick with high-protein whole foods like chicken, fish, eggs, beans, and dairy. 

#2 Don’t lose weight too fast

The idea of instantly dropping pounds is appealing, but losing weight too fast can up the chance of losing more muscle. To reach a healthy pace, work with your prescribing clinician to settle on a medication dose that allows you enough appetite to meet your nutritional needs while resulting in steady weight loss. “A slower rate of weight loss gives the body more time to rely on fat stores while receiving signals that muscle is still needed,” says Juo. “Strength training several times a week can provide the signal the body needs to maintain and build muscle.”

#3 Strength train 2-3x a week

Strength training gives your muscles a reason to stick around instead of being burned for energy while you're taking in fewer calories. Research confirms it can help you hold onto significantly more muscle while losing weight. 

You don't need an elaborate gym routine: Squats, lunges, push-ups, resistance bands, and dumbbells can all provide resistance. For strength-training beginners, Davila recommends starting with two to three 30-minute resistance-training sessions per week and choosing a weight (or resistance level) that makes the final few repetitions challenging while still allowing you to maintain good form. Over time, increase the resistance. The weight you’re using should continue to go up over the course of several months. 

#4 Eat enough overall

GLP-1 medications are designed to reduce appetite, but sometimes that effect can make it difficult to take in enough calories to meet your body’s energy needs — including the energy needed to maintain your muscles, which burn fuel even at rest. Try not to skip meals entirely, even if you’re not starving by breakfast, lunch, or dinner time. And if nausea, vomiting, or other side effects are keeping you from eating enough, tell your prescribing clinician. “A GLP-1 medication should not suppress your appetite completely,” says Davila. “If a patient tells me that they can’t even eat once a day, the dosage may be too high for them.” 

#5 Cover your nutrients

Eating substantially less food can also mean getting fewer vitamins and minerals. Davila points to vitamin D, calcium, thiamine (vitamin B1), iron, zinc, and magnesium as micronutrients to keep an eye on when your overall food intake is low. That doesn't mean everyone taking a GLP-1 needs a long list of supplements; your clinician can help determine whether testing or supplementation makes sense for you.

One supplement Davila recommends for patients starting a GLP-1 medication is creatine. Made naturally by the body from three amino acids we get from food, creatine helps provide energy during muscle contractions. Though research in people taking GLP-1s is limited, creatine supplements have been shown to increase muscle strength and support gains in muscle mass, particularly when combined with resistance training, and new evidence suggests this holds true during weight loss as well.

To recap, here's straightforward summary of the science:

We lose muscle mass during weight loss

A 2026 meta-analysis of 20 randomized controlled trials found that lean mass (which includes muscle) accounted for 25% to 39% of total weight lost with GLP-1 medications.

^{N. Eisa and O. Barood, “ Lean Mass Changes With Incretin Therapy Versus Lifestyle Intervention: A Systematic Review and Meta-Analysis of Randomised Controlled Trials,” Diabetes, Obesity and Metabolism 28, no. 6 (2026): 4818–4827, https://doi.org/10.1111/dom.70666.} 

Resistance training can help you keep muscle

Strength exercise can improve the proportion of weight lost as fat rather than lean mass. In the same meta-analysis, losing weight via lifestyle changes that included resistance training resulted in the most favorable proportions, with only about 18% of weight loss coming from lean mass.

^{N. Eisa and O. Barood, “ Lean Mass Changes With Incretin Therapy Versus Lifestyle Intervention: A Systematic Review and Meta-Analysis of Randomised Controlled Trials,” Diabetes, Obesity and Metabolism 28, no. 6 (2026): 4818–4827, https://doi.org/10.1111/dom.70666.} 

Protein can help too 

Aiming to consume 1.2 to 1.6 grams of protein per kilogram of target body weight per day may help you retain muscle mass as you eat less overall during weight loss, according to a 2026 review of the evidence.

^{Reytor-González C, Loor-Cedeño A, Gavilanes DJ, Matos A, Parise-Vasco JM, Angamarca-Iguago J, Cagua-Ordoñez J, Campuzano-Donoso M, Simancas-Racines D. Higher-Protein Nutrition and Concurrent Exercise in Obesity: A Narrative Review of Body Composition, Metabolic Health, and Physical Function. Nutrients. 2026 Jul 11;18(14):2280. doi: 10.3390/nu18142280.} 

Protein and strength training are key to making sure most of the pounds you drop are excess body fat, and Weight Watchers can help you hit both goals. The Med+ program gives you access to GLP-1s, and a complete lifestyle program on top of that — guiding you to hit daily protein targets and offering live and on-demand strength-training exercises designed to help you retain muscle mass as you lose weight. (You can even request an expert, one-on-one fitness consultation.) This comprehensive approach pays off, especially for anyone who struggles to make healthy habits stick: Med+ members prescribed a GLP-1 and given the lifestyle program increased the number of days they do strength training by 53.2%.*

Some loss of muscle is a typical part of losing weight, including while taking a GLP-1 medication. The evidence suggests that anywhere from 25% to 45% of weight lost with GLP-1s may come from lean mass, although the proportion varies by medication and from study to study. The good news is that GLP-1s cause substantially more fat loss than muscle loss, improving overall body composition. To give yourself the best shot at preserving muscle, add resistance training to your routine, prioritize protein in your diet, eat enough to meet your nutritional needs, and aim for a reasonable rate of weight loss with guidance from your clinician.