GLP-1 agonist medications (Ozempic and Wegovy) and dual GIP/GLP-1 receptor agonist medications (Zepbound and Mounjoaro) are powerful tools for weight loss, but losing weight rapidly can also lead the body to lose too much muscle mass.
While experts continue to debate whether these drugs cause more muscle loss than other means of rapid weight loss, they agree that protecting your muscle mass is crucial for long-term health.
Fortunately, there are ways you can actively preserve your strength while taking GLP-1 medications. The most effective approach combines prioritizing protein intake, strength training regularly, and monitoring your progress with tools other than the bathroom scale.
Everyday Health.
GLP-1 Drugs and Muscle Loss: The Science
When people lose weight, they usually lose some muscle along with fat. In a typical healthy weight loss scenario, about 75 percent of weight loss comes from fat, while roughly 25 percent comes from fat-free mass, including muscle, says Sriram Machineni, MD, an endocrinology, diabetes, and metabolism expert at Montefiore Health Systems in New York City. Fat-free mass includes all the tissues in your body that aren’t fat: muscle, bone, organs, connective tissue, and fluids.
“Even before the advent of GLP-1s, we’ve always known that weight loss is associated with some amount of muscle loss,” says Dr. Machineni.
One reason for this loss is simple physics: As body weight decreases, muscles don’t have to work as hard.
“Whenever we lose weight, our muscles aren’t loaded the same way,” says Machineni. “The body isn’t having to lift the same amount of weight, so the muscles reduce in size because they don’t have to be as large anymore.”
Some early studies raised concerns that GLP-1 users may lose more muscle mass than expected. For instance, initial analyses of the STEP trials involving semaglutide (Ozempic, Wegovy) suggested that users’ lean body mass loss was higher than the anticipated 25 percent observed in traditional weight loss case studies — at times approaching 39 percent of total weight loss.
However, experts note that some errors exist in the study itself. “When that data are reanalyzed, we expect it will probably be similar to what we’ve seen with tirzepatide (Mounjaro), where about 25 percent of weight loss comes from fat-free mass,” says Machineni.
The Risks of Muscle Loss
Rapid weight loss can affect muscle mass, strength, and bone health, especially in older adults, postmenopausal women, sedentary individuals, and people with chronic conditions like arthritis, diabetes, heart disease, and kidney disease who are already at risk of muscle loss.
Losing too much muscle mass can lead to:
Decreased Strength Less muscle directly reduces strength, affecting both physical fitness and basic daily function.
Frailty Age-related progressive muscle and strength loss leads to frailty, making everyday activities more difficult.
Increased Risk of Falls Muscle loss also diminishes your sense of stability and overall balance, raising the likelihood of falls.
Poor Bone Health Reduced muscle support can weaken bones over time, increasing fracture risk.
Slower Metabolism With less muscle, the body burns fewer calories at rest, which can make weight maintenance more difficult.
Struggles With Long-Term Weight Management Muscle loss also makes it easier to regain weight — often as fat — if medication is stopped or its effects fade.
Even modest muscle loss matters. “It’s not just a side effect; it’s a metabolic liability,” says Sangeeta Kashyap, MD, assistant chief of clinical affairs at New York-Presbyterian/Weill Cornell Medical Center. “Skeletal muscle is not just tissue that helps us move; it’s our most metabolically active organ. It burns 80 percent of glucose post-meal and 20 to 30 percent of fat at rest, regulates insulin sensitivity, supports immune health, and helps maintain our resting metabolic rate.”
Prevention Strategies
Several practical strategies can help you protect your lean mass while working to lose weight.
Eat Enough Protein
Protein is essential for repairing and maintaining muscle, especially during weight loss.
GLP-1 medications can reduce appetite, making it challenging to eat enough, increasing the importance of choosing wholesome foods. “When calories are restricted, adequate protein becomes essential to maintain muscle,” says Dr. Kashyap, who recommends working with a nutritionist, if possible, to make every meal count.
Currently, there aren’t specific protein consumption guidelines for people taking GLP-1 medications, as further research is needed to understand the unique nutritional needs of this population. However, Machineni suggests aiming for higher-than-average protein intake. “The goal is 1 to 1.5 grams per kilogram of body weight,” he says. “For someone who weighs about 220 pounds, that’s roughly 100 to 150 grams per day.”
For perspective, one large egg contains about 6 grams of protein, and a typical serving of boneless, skinless chicken breast provides nearly 26 grams of protein.
It’s also important to spread out your protein intake throughout the day, including protein at every meal. “The maximum your body can use at one time is about 30 grams,” says Machineni. Protein-rich shakes containing 30 to 40 grams of protein with minimal sugar or fat can be an easy, healthy option when your appetite is low.
Strength Training
If you’re taking a GLP-1 medication, strength training is essential for preventing too much fat-free mass loss. Normally, when you eat less, your body may try to burn muscle for energy, which slows your metabolism. Strength training sends a signal to your body to keep building and repairing muscle fibers instead.
Without resistance exercise, you risk losing muscle and bone mass, which can slow your metabolism, sap your energy, and impact your long-term health, says Kashyap. Even on days that you don’t exercise, building and maintaining muscle helps your body burn more fuel than it would otherwise.
“Muscle acts as your body’s engine for burning calories and managing blood sugar,” says Kashyap. “The more muscle you have, the more efficiently your body processes energy.”
The benefits of strength training extend to your bones as well. Weight-bearing and resistance exercises place healthy stress on bones, encouraging them to become denser and stronger, which is an important step in reducing your risk of osteoporosis, especially during periods of weight loss.
Adults should aim for at least two full-body strength training sessions each week. Focusing on compound exercises that work multiple major muscle groups at a time, such as push-ups, rows, squats, hip bridges, deadlifts, and lunges, can be a smart and effective way to integrate resistance training into your routine.
If you’re taking a GLP-1 medication, side effects like nausea or gastrointestinal discomfort may sometimes make exercise feel more challenging. Scheduling your workouts for times of the day when your symptoms are less severe may make it easier to stay consistent.
As with any new exercise routine, it’s important to check with your healthcare provider before getting started. Ease in gradually, starting with fewer or shorter sessions and increasing your intensity over time. You may also consider working with a certified personal trainer. Many gyms offer free introductory sessions that can help you learn proper form and feel more confident.
Monitor Your Progress
Since it can be difficult to see whether you’re losing muscle by simply looking in the mirror or stepping on the bathroom scale, it’s important to talk to your doctor about other effective means of monitoring your body composition when you are taking a GLP-1 medication.
“Body weight alone is a crude metric of health,” says Kashyap. “Measuring body composition (fat versus lean mass) should become routine in the management of patients on GLP-1 medications.”
Inquire about a body composition test like a bioelectrical impedance assessment (BIA) or a dual energy X-ray absorptiometry (DEXA/DXA) scan to gain better insights than a scale can provide. It can also be helpful to keep a data log of the strength and functional fitness improvements you experience over time.
The Takeaway
While GLP-1 medications are effective for weight loss, rapid weight reduction can lead to significant loss of fat-free mass, including muscle.
Losing too much muscle while taking a GLP-1 medication can result in decreased strength, slower metabolism, increased risk of falls, and a higher likelihood of regaining weight once you stop taking the medication.
Experts recommend protecting your muscle mass by prioritizing a high protein intake and performing at least two full-body strength training sessions per week.
Since a standard bathroom scale cannot distinguish between fat and muscle loss, you should consider using more advanced tools like DEXA scans or BIA tests to track changes in your body composition.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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Chang X et al. Regulation of Bone Health Through Physical Exercise: Mechanisms and Types. Frontiers in Endocrinology. December 6, 2022.
Metabolism and Weight Loss: How You Burn Calories. Mayo Clinic. October 8, 2022.
Abdullah bin Ahmed I. A Comprehensive Review on Weight Gain Following Discontinuation of Glucagon-Like Peptide-1 Receptor Agonists for Obesity. Journal of Obesity. May 10, 2024.
Christensen S et al. Dietary Intake by Patients Taking GLP-1 and Dual GIP/GLP-1 Receptor Agonists: A Narrative Review and Discussion of Research Needs. Obesity Pillars. September 2024.
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Adam Gilden, MD, MSCE, is an associate director of the Obesity Medicine Fellowship at University of Colorado School of Medicine and associate director of the Colorado University Medicine Weight Management and Wellness Clinic in Aurora. Dr. Gilden works in a multidisciplinary academic center with other physicians, nurse practitioners, registered dietitians, and a psychologist, and collaborates closely with bariatric surgeons.
Gilden is very involved in education in obesity medicine, lecturing in one of the obesity medicine board review courses and serving as the lead author on the Annals of Internal Medicine article "In the Clinic" on obesity.
He lives in Denver, where he enjoys spending time with family, and playing tennis.
Susan Jara is a health communications strategist and writer with more than 15 years of experience transforming complex medical information into clear, accurate, and engaging content for diverse audiences of patients and caregivers. She specializes in patient education, health literacy, and SEO-driven content strategy, with expertise across chronic disease, mental health, addiction, arthritis, autoimmune conditions, and wellness.
Susan holds a bachelor’s degree in journalism and media studies from New York University’s Gallatin School of Individualized Study. Her career includes leadership roles at the Global Healthy Living Foundation and Health Monitor Network, where she developed multichannel health content across web, email, podcasts, video, social media, and print. Susan's work reaches millions of readers each year, and she collaborates with leading healthcare providers, researchers, advocacy groups, and industry partners to create resources that reach millions of readers each year.
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