The Study
The effectiveness of protein supplements on athletic performance and post-exercise recovery − a Bayesian multilevel meta-analysis of randomized controlled trials
This study looked at lots of other experiments where athletes took protein supplements. It found that when people got extra calories from protein, they sometimes performed better. But we can't say for sure it was the protein that helped — it might have just been the extra food energy.
Analysis score
Maximum 100 for a systematic review with meta-analysis.
Where the score came from
Protein supplements seem to help athletes perform better and recover faster, but only when they eat more calories overall. It might not be the protein itself—it could just be eating more food.
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 560 / 100
Quality score
The highest quality evidence. These studies systematically search, appraise, and synthesize results from multiple individual studies, providing the most reliable summary of current knowledge.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The improvements are noticeable, but they may come from extra energy, not just protein.
- 2For real-world athletes, more food might explain the boost, not the protein supplement alone.
- 3Protein helped endurance (0.37), strength (0.72), and recovery (0.83).
- 4With carbs, endurance improved even more (0.57).
- 5Most gains happened when people ate more total calories.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of the International Society of Sports Nutrition
Year
2025
Authors
Shiao Zhao, Xiaoyu Zhang, Taihe Liang, Sanfan Ng, Yiran Liu, Ziheng Ning
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.