The Study
Effect of Dietary Protein on Fat-Free Mass in Energy Restricted, Resistance-Trained Individuals: An Updated Systematic Review With Meta-Regression
This study looks at lots of other studies and tries to find a pattern. It found that people who eat more protein while lifting weights and eating less food tend to keep more muscle. But we can't say for sure that protein is the reason — it's just linked.
Analysis score
Maximum 100 for a systematic review with meta-analysis.
Where the score came from
When people who lift weights eat less food to lose fat, they want to keep their muscle. This study looked at whether eating more protein helps protect muscle during fat loss.
Where does this study sit?
Systematic Reviews & Meta-analyses
Max 100Randomized Trials
Max 90Cohort Studies
Max 72Case-Control
Max 58Cross-Sectional
Max 44Case Reports & Series
Max 30Expert Opinion
Max 533 / 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.
- 1Yes, the result is meaningful—especially for athletes or lifters trying to stay strong while getting leaner.
- 2More protein leads to better muscle retention.
- 3The benefit is clearer when protein is measured per kilogram of muscle, not total weight.
- 4Men and leaner people see stronger effects.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Strength & Conditioning Journal
Year
2025
Authors
Martin C. Refalo, Eric T. Trexler, Eric R. Helms
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.