The Study
Effects of once-weekly semaglutide on regional body composition in overweight or obese adults
This study followed 47 people who took a weight loss drug and made lifestyle changes for 12 weeks. They measured how much fat and muscle they lost in different body parts. But because there was no comparison group of people who didn't take the drug, we can't say for sure the drug caused the changes—they could be from the lifestyle changes. So, we can only describe what happened, not prove the drug works.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
This study looked at how semaglutide (a weight-loss drug) changes body shape in overweight adults. People took the drug and got lifestyle advice for 12 weeks.
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 560 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Losing some muscle is common with weight loss, but the improvement in muscle-to-fat ratio suggests the body composition change is still beneficial.
- 2The preferential loss of belly fat is particularly good for health.
- 3On average, people lost 6.77 kg (about 15 lbs).
- 4About 70% of that was fat and 30% was muscle.
- 5Belly fat decreased more than other fat.
- 6The ratio of muscle to fat got better.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Metabolism and Target Organ Damage
Year
2026
Authors
Yishan Ma, Bixuan Tang, Yingjuan Zeng, Yingying Zhan, Li Cong, Fang Hu
Related Content
Claims (6)
People taking GLP-1 receptor agonists for weight loss lose muscle mass in addition to fat mass.
Overweight and obese adults who received weekly semaglutide injections and lifestyle advice for 12 weeks lost visceral fat by 21.3% and subcutaneous fat by 16.1%. The proportional reduction in visceral fat was significantly greater than in subcutaneous fat.
Overweight adults taking semaglutide weekly for 12 weeks along with lifestyle counseling lose muscle mass in most parts of the body, especially the legs (about half a kilogram per leg). However, their muscle-to-fat ratio increases, meaning muscle is maintained relative to fat loss.
In overweight or obese adults, taking semaglutide once a week along with lifestyle counseling for 12 weeks is associated with an average weight loss of 6.77 kg. This weight loss consists of 4.75 kg of fat loss and 2.02 kg of muscle loss, and the muscle-to-fat ratio increases by 0.15.
Overweight or obese adults who take a weekly semaglutide injection and follow a lifestyle program for 12 weeks lose fat from all body areas, with the most fat loss happening in the belly area.
Overweight or obese adults who take semaglutide once a week and follow a lifestyle program for 12 weeks show improvements in several health markers, such as lower blood sugar, better liver enzymes, reduced uric acid, and lower total cholesterol.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.