Free 60-second assessment

Are You Losing Muscle on Your GLP-1 Medication?

Up to 40% of weight lost on Ozempic, Wegovy, or Mounjaro can be muscle — not fat. Take this free, evidence-based assessment to find out your risk level and get personalized recommendations.

25–40%

of weight lost is lean mass

6.9 kg

average lean mass lost (STEP 1)

60 sec

to complete the assessment

Question 1 of 5

How old are you?

This assessment is for informational and educational purposes only. It is not a medical diagnosis and does not replace professional medical advice. Always consult your healthcare provider before making changes to your diet, exercise routine, or medication.

Why Muscle Loss on GLP-1 Matters

GLP-1 receptor agonists like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are remarkably effective for weight loss. But clinical trials consistently show that a significant portion of that weight loss — between 25% and 40% — comes from lean mass, not fat. In the landmark STEP 1 trial, participants lost an average of 6.9 kg of lean mass over 68 weeks.

Muscle is not just about appearance. It drives your resting metabolism, protects your joints, supports cardiovascular fitness, and is one of the strongest predictors of long-term health. Losing too much muscle during rapid weight loss can lead to sarcopenia, metabolic slowdown, and increased risk of weight regain.

The good news: muscle loss on GLP-1 therapy is not inevitable. Research shows that combining adequate protein intake (1.2–1.6g/kg/day), regular resistance training (2–3 sessions per week), and monitoring body composition can significantly reduce lean mass loss — even during substantial weight reduction.

How the Assessment Works

This free assessment evaluates five evidence-based risk factors for muscle loss during GLP-1 treatment: your age, resistance training frequency, daily protein intake, rate of weight loss, and treatment duration. Each factor is weighted based on published clinical data.

Your results include a personalized risk level (low, moderate, or high) and specific, actionable recommendations to protect your muscle while continuing your GLP-1 treatment. The assessment takes about 60 seconds.

Frequently Asked Questions

How much muscle do you lose on GLP-1 medications?

Clinical trials show that 25–40% of total weight lost on GLP-1 medications comes from lean mass, which includes muscle. In the STEP 1 trial of semaglutide, participants lost an average of 6.9 kg of lean mass over 68 weeks alongside 17.3 kg of total weight loss.

Can you prevent muscle loss while taking Ozempic or Wegovy?

Yes. Research shows that combining adequate protein intake (1.2–1.6g per kg of body weight daily), regular resistance training (2–3 sessions per week), and a gradual weight loss pace can significantly reduce muscle loss during GLP-1 treatment.

How much protein should I eat on GLP-1 medication?

Most experts recommend 1.2 to 1.6 grams of protein per kilogram of body weight per day during GLP-1 treatment. Some research suggests up to 2.0g/kg may be beneficial. Distributing protein across 3–4 meals (20–40g per meal) optimizes muscle protein synthesis.

What is the Kiro Muscle Loss Risk Assessment?

It is a free, 60-second quiz that evaluates five key risk factors for muscle loss during GLP-1 treatment: age, resistance training frequency, protein intake, weight loss speed, and treatment duration. You receive a personalized risk score and actionable recommendations.

Who is most at risk for muscle loss on GLP-1 drugs?

Adults over 50, those with low protein intake, people not doing resistance training, and those losing weight rapidly (over 4 kg per month) are at highest risk. The combination of multiple risk factors significantly increases the likelihood of clinically meaningful muscle loss.

Sources

  1. Wilding JPH et al. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity. N Engl J Med, 384:989–1002. STEP 1 trial.
  2. Sanchis-Gomar F et al. (2025). Preserving the Metabolic Engine: Muscle as the Therapeutic Target. Curr Cardiol Rep, 28(1):2. PMID: 41400708.
  3. Rossi G et al. (2026). Muscle loss and GLP-1R agonists use. Acta Diabetol, 63(2):333–342. PMID: 41201615.
  4. Mechanick JI et al. (2025). Strategies for minimizing muscle loss during use of incretin-mimetic drugs. Obes Rev, 26:e13841.
  5. Butsch WS et al. (2025). Nutritional Deficiencies and Muscle Loss in Adults with T2D Using GLP-1 RAs. Obesity Pillars, 15:100186. PMID: 40584822.