One of the most exciting advances in metabolic medicine has been the GLP-1 family of weight-loss medications, with semaglutide (Wegovy/Ozempic) leading the charge. Patients are experiencing transformational fat loss, better blood-sugar control, and renewed hope. Yet a quieter conversation has been murmuring in exam rooms and social-media groups alike: “Will I lose muscle along the way?”
As a clinician-researcher who cherishes both the science and the lived human experience, I’ve shared those concerns. Muscle isn’t just about aesthetics – it’s our metabolic engine, our glucose sponge, a pillar of resilience as we age. Losing too much lean mass can leave us weaker, hungrier, and more insulin-resistant in the long run.
What the New Study Tells Us
At this year’s ENDO 2025 meeting in San Francisco, Dr. Melanie Haines and colleagues presented a small but revealing three-month study of 40 adults with obesity (Endocrine Society press release). Twenty-three participants used semaglutide; the remaining seventeen followed a lifestyle program without medication. Weight loss happened in both groups, but the spotlight was on how that weight was lost — and the role protein played.
- On average, about 40 % of semaglutide-related weight loss came from lean mass, mirroring earlier data.
- Women, older adults, and those consuming less protein lost the greatest proportion of muscle.
- Higher protein intake was linked to better muscle preservation and, intriguingly, to larger improvements in HbA1c — our key marker of long-term blood-sugar control.
Why Lean Mass Matters More Than Ever
We sometimes treat the scale like a judge and jury, yet body composition tells the fuller story. Muscle tissue:
- Soaks up glucose after meals, taming post-prandial blood-sugar spikes.
- Stimulates resting metabolic rate, preventing the dreaded “metabolic slowdown.”
- Protects bones by generating mechanical load and secreting myokines that cross-talk with bone cells.
- Supports balance, posture, and everyday independence.
When GLP-1 therapy trims fat but also nibbles away at muscle, those benefits erode. The ENDO 2025 findings nudge us to upgrade our toolkit: medication plus nutrition, movement, and mindful rest.
How Much Protein Is Enough?
Most of the semaglutide users in Dr. Haines’ study ate less than 1.0 g of protein per kilogram of body weight per day — below what sports dietitians consider muscle-sparing on a hypocaloric diet. Based on the broader literature, I steer patients toward the following practical range:
- 1.2 – 1.6 g/kg of current body weight daily for non-athletes in active weight loss.
- Distribute protein over three to four meals, aiming for 25-35 g per meal to maximally stimulate muscle protein synthesis.
- Favor high-quality sources (eggs, poultry, fish, Greek yogurt, legumes, soy foods, protein powders if needed) and pair them with fiber-rich carbs and healthy fats for satiety and micronutrients.
For a 200-lb (91-kg) individual, that’s roughly 110-145 g of protein per day. Yes, it requires intention — but so does injecting a weekly medication. Both are acts of self-care.
Resistance Training: The Unsung Co-Pilot
No conversation about muscle preservation is complete without movement. While ENDO 2025 focused on diet, progressive resistance training magnifies the protective effect of protein. Two to three full-body sessions per week — using free weights, machines, or even resistance bands — send the “stay, don’t stray” signal to muscle fibers.
The synergy is powerful: protein provides raw materials; mechanical tension tells the body where to deposit them.
Putting It All Together
To my patients starting semaglutide, I now present a four-pillar framework:
- Customized Protein Plan – Calculate your daily target and create meal templates.
- Strength-Focused Exercise – Schedule resistance workouts like medical appointments.
- Micronutrient Support – Ensure vitamin D, calcium, magnesium, and B-vitamins are sufficient for muscle metabolism.
- Restorative Sleep & Stress Care – Chronic stress hormones break down muscle; deep sleep rebuilds it.
Semaglutide remains a remarkable ally in the fight against obesity. The ENDO 2025 study doesn’t diminish its value; it refines our approach. Rather than surrendering lean tissue, we can protect — even build — muscle by weaving high-protein nutrition and strength training into the medication narrative.
Looking Forward
Research continues. Combination therapies like semaglutide plus the muscle-promoting antibody bimagrumab are showing promise for even better body-composition outcomes (Pharmacy Times report). Meanwhile, simple lifestyle levers are already within reach. If you are on a GLP-1 journey, talk with your healthcare team about a personalized protein and fitness plan. Your future self — stronger, steadier, and metabolically resilient — will thank you.
