Are GLP-1s Making You Skinny Fat? What You Need to Know
GLP-1 medications like Ozempic, Wegovy, Zepbound, and Mounjaro are rapidly gaining popularity for their powerful weight loss benefits. For many women, especially those over 40, these drugs have created hope where traditional diets and exercise plans failed. But while the scale might be going down, there’s a growing concern that’s not being talked about enough:
Are you losing fat—or are you losing muscle?
As a fitness and nutrition coach who has worked with thousands of women over the past 20 years, I’ve seen firsthand how weight loss doesn’t always mean better health or a stronger body. That’s especially true with GLP-1 medications.
So today, I want to break down the science, the risks, and the solutions—so you can lose fat, stay strong, and avoid becoming what many call “skinny fat.”
What Does “Skinny Fat” Actually Mean?
The term “skinny fat” refers to a body that may appear smaller, with weight loss showing on the scale or in clothing size—but with a high body fat percentage and low muscle mass underneath.
You might shrink in size but feel softer, weaker, or less defined. That’s because you’ve lost not just fat, but also lean muscle mass—an outcome that can actually slow your metabolism and make long-term fat loss harder to maintain.
Muscle is active tissue. It burns calories at rest, supports your joints, improves posture, and helps regulate blood sugar. Losing it impacts much more than how your body looks. It affects how your body functions.
What the Research Says About GLP-1s and Muscle Loss
GLP-1 medications work by mimicking a hormone that slows digestion, reduces appetite, and helps you feel full longer. This leads to a significant reduction in calorie intake—and yes, weight loss.
But the type of weight being lost matters.
Studies like the STEP-1 trial found that up to 39% of the weight lost on semaglutide (the compound in Ozempic and Wegovy) came from lean mass—including muscle. Another 2023 study published in The Journal of Cachexia, Sarcopenia and Muscle found similarly dramatic declines in fat-free mass in patients using GLP-1s without structured exercise or nutrition plans.
I’ve seen this firsthand in women who come to me after rapid weight loss with GLP-1s. They’re smaller, yes—but also weaker, softer, and often more frustrated than when they began.
Women Over 40: Why You’re at Higher Risk
Hormonal changes starting in our late 30s and early 40s naturally lower muscle mass—a condition known as sarcopenia. When estrogen drops during perimenopause and menopause, this loss accelerates. Add in the appetite suppression from GLP-1s and a lack of strength training, and you’ve got the perfect storm for rapid muscle breakdown.
This is why so many women over 40 say, “I’ve lost the weight, but I still don’t feel strong—or look how I expected.”
How to Stay Strong and Healthy on GLP-1s
If you’re currently using a GLP-1—or considering one—there are three key strategies to protect your body and maintain your strength:
1. Strength Train 3–4 Times Per Week
Focus on compound movements like squats, deadlifts, overhead presses, and rows. You don’t need long workouts—30 to 45 minutes of intentional resistance training is enough.
Training tells your body: “We still need this muscle.”
2. Prioritize Protein
Aim for 25–35 grams of protein per meal, and consider 0.8–1 gram of protein per pound of your goal body weight.
If appetite is low, use easier options like protein shakes, Greek yogurt, cottage cheese, or lean meats. Every gram matters when you’re working to preserve lean tissue.
3. Support Recovery
Sleep 7–9 hours a night. Stay hydrated. Move your body with light activity like walking and stretching. These basics help your body rebuild and maintain the muscle you’re training for.
Progress Is More Than the Scale
The number on the scale doesn’t tell the whole story. Instead, track:
- Progress photos
- Body measurements (waist, hips, thighs)
- Strength performance like my FITBODY Fit Test
- Energy levels and recovery
Losing 20 pounds of fat is fantastic. Losing 10 pounds of fat and 10 pounds of muscle? That’s a setback you don’t need. You’re not just trying to shrink your body. You’re building one that supports you for years to come.
Want Help Staying Strong on Your Journey?
GLP-1s can be a powerful part of your weight loss process—but they’re not a standalone solution.
In my coaching programs, I help women over 40 build muscle, lose fat, and feel strong, energized, and confident—whether they’re using a GLP-1 medication or navigating life after.
If you want a personalized training and nutrition plan designed for your body, your goals, and your stage of life, I’d love to help. Visit my Online Fitness Coaching Page to learn more about working with me 1-on-1. You deserve to feel amazing in your body—and I’m here to help you get there.
Scientific Research Appendix
- Wilding, John P.H., et al.
“Once-Weekly Semaglutide in Adults with Overweight or Obesity.” New England Journal of Medicine, vol. 384, no. 11, 2021, pp. 989–1002.
https://doi.org/10.1056/NEJMoa2032183
This study (STEP-1 trial) demonstrated that participants using semaglutide lost a significant amount of weight, with approximately 39% of the weight loss attributed to lean mass, raising concerns about muscle preservation during GLP-1-induced weight loss.
- Collet, Thomas-H., et al.
“Weight Loss Associated with Semaglutide Is Primarily Fat Mass Loss with Minor Lean Mass Loss.” The Journal of Clinical Endocrinology & Metabolism, vol. 105, no. 10, 2020, pp. e3610–e3618.
https://doi.org/10.1210/clinem/dgaa531
This paper supports the importance of resistance training and protein intake during GLP-1 therapy, suggesting that body composition improvements depend on structured lifestyle support.
- Heymsfield, Steven B., et al.
“Skeletal Muscle Mass and Composition in Adults with Obesity: The Role of Weight Loss and Maintenance.” Obesity Reviews, vol. 15, no. 11, 2014, pp. 811–822.
https://doi.org/10.1111/obr.12212
Highlights the risk of sarcopenic obesity and underscores the critical need for strength training and protein to preserve skeletal muscle during weight loss, especially in women over 40.
- Wharton, Sean, et al.
“Obesity in Adults: A Clinical Practice Guideline.” Canadian Medical Association Journal, vol. 192, no. 31, 2020, pp. E875–E891.
https://doi.org/10.1503/cmaj.191707
Recommends that patients using pharmacotherapy for obesity, such as GLP-1 agonists, be provided with structured nutrition and exercise programs to minimize lean mass loss and support metabolic health.