If you are taking Ozempic, Wegovy, Mounjaro or any other GLP-1 medication, the scale is probably moving in the right direction. The question is, what is happening to the rest of your body while that number goes down?
Here is the part your doctor may not have spent enough time on. Clinical trials, including the STEP 1 trial for semaglutide and the SURMOUNT-1 trial for tirzepatide, showed that 26%-40% of the total weight loss on these medications was lean tissue, not fat.1,2 A 2025 case series from Texas Tech University, published in Sage Open Medical Case Reports, took it a step further and found that patients who combined their GLP-1 medication with resistance training three to five days per week, along with a higher protein intake, were able to preserve or even gain lean tissue during treatment.3
These results tell you two things: the muscle loss is real and significant, and strength training is the proven way to stop it.
Muscle is the engine behind your metabolism
Muscle burns calories even while you are sitting still. When you lose it, your resting metabolic rate drops. That means the moment you stop taking the medication or taper your dose, weight regain becomes much more likely because the engine that was keeping you lean has slowed.
For adults over 40, this compounds a problem that is already happening naturally. After 50, most people lose 3%-5% of their muscle mass per decade.4 Layer GLP-1 muscle loss on top of age-related muscle loss, and you are accelerating a decline that directly affects your mobility, your balance, your joint health and your independence.
Strength over cardio
Your doctor probably told you to exercise. So, you started walking. Walking is great for your heart and your mood, but it does not create the load your muscles need to stay strong.
The European Association for the Study of Obesity states that resistance training, not aerobic exercise, preserves lean body mass during weight loss.5 Walking 10,000 steps a day will not change the muscle loss equation; strength training is the answer.
The research converges on the same recommendation: resistance training two to three times per week using compound movements like squats, deadlifts, rows and presses; progressive overload so the challenge increases over time; and aerobic activity three to five times per week as a complement, not the foundation. Strength first and cardio second.
Knowledge and flexibility matter
GLP-1 side effects, including nausea, reduced appetite, fatigue and dizziness, are common, especially during dose adjustments. Your training program needs to flex around those realities. Some days you feel strong and your coach pushes you; some days you are fighting nausea and the session adapts. That is exactly why working with a personal trainer who understands GLP-1 medications makes such a difference. A random gym routine cannot adjust to how you feel on any given day, but a
good coach can.
Lead with protein
Most people on GLP-1 are simply not eating enough protein to support muscle retention. Guidelines recommend 1.2-2.0 grams of protein per kilogram of body weight daily for GLP-1 users.6 For a 160-pound person, that is roughly 87-145 grams per day. When your appetite is gone, hitting those numbers requires planning. Every meal needs to lead with protein.
Building muscle while losing fat means you are creating a body that can maintain its new weight after the prescription ends. Your metabolism stays higher and your body has the engine to support the weight loss long-term.
The medication handles the calorie deficit. The hard part is making sure what is left when the weight comes off is a body that is strong, functional and built to maintain results.
Gerry Washack is the owner of Strong Republic Personal Training with locations in Palm Desert, La Quinta and Palm Springs. Visit www.strongrepublicpersonaltraining.com.
References: 1) Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021;384(11):989-1002; 2) Look M, Dunn JP, Kushner RF, et al. Body Composition Changes During Weight Reduction With Tirzepatide in the SURMOUNT-1 Study of Adults With Obesity or Overweight. Diabetes, Obesity and Metabolism. 2025; 3) Tinsley GM, Nadolsky S. Preservation of Lean Soft Tissue During Weight Loss Induced by GLP-1 and GLP-1/GIP Receptor Agonists: A Case Series. SAGE Open Medical Case Reports. 2025;13; 4) Volpi E, Nazemi R, Fujita S. Muscle Tissue Changes With Aging. Current Opinion in Clinical Nutrition and Metabolic Care. 2004;7(4):405-410; 5) https://easo.org/; 6) Bauer J, Biolo G, Cederholm T, et al. Evidence-Based Recommendations for Optimal Dietary Protein Intake in Older People. Journal of the American Medical Directors Association. 2013;14(8):542-559.
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