The Study
Effect of Incretin-Based and Nonpharmacologic Weight Loss on Body Composition : A Systematic Review.
This study looked at many different experiments where people took weight-loss drugs and measured how their bodies changed. It found that these drugs usually make people lose fat, but sometimes also make them lose muscle. But because the studies were done differently, we can't say for sure exactly how much muscle is lost every time.
Analysis score
Maximum 100 for a systematic review.
Where the score came from
This study looked at whether popular weight-loss drugs like semaglutide and tirzepatide cause more muscle loss than diet and exercise.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 546 / 100
Quality score
The highest quality evidence. Systematic reviews and meta-analyses that pool randomized controlled trials, giving the most reliable summary of experimental evidence.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Losing muscle during weight loss is common—even with dieting—but these drugs cause it at similar or higher rates, and we don’t know if it affects strength or daily function.
- 2On average, about 28% of weight lost from these drugs came from muscle.
- 3In 65% of the studies, muscle loss was over 25% of total weight lost.
- 4About 38% of diet/exercise groups also lost more than 25% muscle.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Annals of internal medicine
Year
2026
Authors
J. Batsis, Alessandro Gavras, Danae C. Gross, C. Cheever, B. R. da Silva, Luiz Fernando Meira Filho, E. Jones, Dakota J Batchek, Simone G Khandpekar, Rohan Patel, Bilal Awkal, A. Pape, Maria Bahna, Mauro Zamboni, C. M. Prado
Related Content
Claims (10)
When people lose weight using GLP-1 agonist medications, the amount of lean mass lost relative to total weight loss differs between studies, ranging from as low as 15% to as high as 60%.
When older adults are prescribed GLP-1 agonists, the total cost of their prescription medications increases for Medicare.
As people get older, they naturally lose muscle and bone mass at a faster rate than when they were younger.
When people lose weight using GLP-1 agonists, about half of the weight lost comes from muscle and bone tissue.
People using GLP-1 agonists for weight loss lose more muscle mass than those who lose weight without medications.
When people lose weight through diet and exercise, their muscle mass decreases beyond established thresholds in almost half of cases.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.