Researchers looked at 75 studies involving 1,206 athletes to understand whether protein supplements actually help with athletic performance and recovery. They found that protein supplements did show some benefits compared to doing nothing, but the benefits were smaller than many people think. Interestingly, the biggest benefits appeared in studies where athletes taking supplements also ate more total calories than the comparison group. This suggests the extra calories—not just the protein—might be responsible for the improvements. The research suggests that if athletes want to use protein supplements, about 2 grams of protein per kilogram of body weight per day appears to be the most helpful amount.

The Quick Take

  • What they studied: Whether protein supplements help athletes run faster, jump higher, build muscle, and recover better after workouts compared to not taking supplements or taking other types of supplements.
  • Who participated: 1,206 athletes across 75 different research studies. The studies looked at various types of athletes doing different sports and training activities.
  • Key finding: Protein supplements showed modest benefits compared to no supplement at all. However, when researchers looked more carefully, they discovered that the biggest improvements happened in studies where the supplement group was also eating more total calories. This suggests the extra calories might deserve some credit for the improvements, not just the protein itself.
  • What it means for you: If you’re an athlete considering protein supplements, they may provide small benefits, but they’re not a magic solution. The benefits appear to come partly from eating more overall calories. Eating enough total food and getting adequate protein from regular meals might be just as important as taking supplements. Talk to a coach or nutritionist before starting supplements.

The Research Details

This was a meta-analysis, which means researchers gathered and combined results from many smaller studies to find bigger patterns. They searched seven different scientific databases and found 6,129 studies about protein supplements and athletic performance. Two independent reviewers carefully selected which studies to include, checking each one for quality and potential bias. They ended up with 75 studies that met their standards.

The researchers used advanced statistical methods called Bayesian multilevel modeling to combine all the data. This approach is like having a sophisticated calculator that can handle complex information from many different studies, even when those studies used different methods or measured slightly different things. They also checked whether the results might be biased by looking at publication bias—the tendency for studies with positive results to be published more often than studies with negative results.

Using a meta-analysis approach is important because individual studies can be small or have limitations. By combining 75 studies together, the researchers could see clearer patterns and more reliable conclusions. The Bayesian statistical method they used is particularly good at handling uncertainty and complex data, which is important when combining studies that measured things in different ways. This approach gives us more confidence in the findings than any single study could provide.

This study was registered in advance (PROSPERO), which is a good sign that researchers planned their analysis carefully and weren’t just cherry-picking results. Two independent reviewers checked each study, which reduces the chance of mistakes. The researchers also checked for publication bias, showing they were thinking critically about their data. However, the quality of the final conclusions depends on the quality of the 75 studies included—if many of those studies had problems, the meta-analysis results would be less reliable. The fact that significant benefits only appeared in studies with unmatched calories raises questions about what’s really causing the improvements.

What the Results Show

When researchers looked at protein combined with carbohydrates (a common type of supplement), they found it helped endurance performance—like running or cycling longer—compared to a placebo (fake supplement). The improvement was modest but measurable.

Pure protein supplements alone also showed benefits for endurance performance and muscle strength compared to placebo. Athletes taking protein supplements appeared to perform slightly better and build muscle a bit faster than those taking nothing.

For recovery after exercise, pure protein supplements appeared to help the body rebuild its energy stores (called glycogen) better than carbohydrate supplements alone.

However, here’s the important catch: when researchers looked more carefully at which studies showed the biggest benefits, they noticed something crucial. All the studies that showed statistically significant improvements were ones where the protein supplement group was eating more total calories than the control group. In studies where both groups ate the same total number of calories, the benefits of protein supplements largely disappeared. This is a major finding because it suggests the extra calories might be doing most of the work, not the protein itself.

The research also examined whether the type of protein (like whey, casein, or plant-based), when you take it, and how much you take makes a difference. The analysis suggested that taking about 2 grams of protein per kilogram of body weight per day (roughly 0.9 grams per pound) appeared most effective. For a 150-pound athlete, this would be about 135 grams of protein daily. The timing of when you take protein supplements and the specific source of protein showed less dramatic differences than the total amount.

This research builds on decades of sports nutrition studies. Previous research has suggested protein is important for muscle building and recovery, and this meta-analysis confirms that protein supplements do provide some benefit. However, this study goes further by questioning whether the benefits come from protein specifically or from the extra calories that often come with supplements. This is an important refinement of what we thought we knew—it suggests that previous research might have overestimated how much protein supplements help because those studies weren’t carefully controlling for total calorie intake.

The biggest limitation is that the researchers couldn’t control how the original 75 studies were designed. Some studies were better quality than others. The fact that benefits only appeared in studies with unmatched calories is concerning—it means we can’t be sure protein supplements actually help when people eat the same total amount of food. The studies also mostly looked at young, healthy athletes, so results might not apply to older people, beginners, or people with certain health conditions. Additionally, many studies were relatively short-term, so we don’t know if benefits continue over months or years. Finally, the research doesn’t tell us much about whether whole food sources of protein (like chicken, eggs, or beans) work differently than supplements.

The Bottom Line

If you’re an athlete: Protein supplements may provide small benefits for performance and recovery, but they’re not essential. Getting enough total calories and adequate protein from regular food is probably just as important. If you choose to use supplements, aim for about 2 grams of protein per kilogram of body weight daily (roughly 0.9 grams per pound). For a 150-pound person, that’s about 135 grams per day. This can come from food, supplements, or a combination. Confidence level: Moderate. The evidence shows small benefits, but the benefits might come from extra calories rather than protein specifically.

This research matters most for competitive athletes and serious fitness enthusiasts who are trying to optimize their performance. It’s less relevant for casual exercisers or people just trying to stay healthy. If you’re training hard multiple times per week and trying to build muscle or improve endurance, protein intake matters more. If you exercise casually a few times per week, you probably don’t need supplements—regular food is fine. People with certain health conditions (like kidney disease) should talk to their doctor before taking protein supplements.

If protein supplements are going to help you, you’d likely notice small improvements within 4-8 weeks of consistent training and supplementation. However, the improvements are modest—don’t expect dramatic changes. The bigger picture is that consistent training and adequate overall nutrition matter much more than supplements. Benefits would continue as long as you maintain the supplementation and training, but stopping supplements wouldn’t cause you to lose gains quickly.

Want to Apply This Research?

  • Track daily protein intake in grams and total daily calories. Set a target of 2 grams of protein per kilogram of body weight and monitor whether you’re hitting that target from all sources (food plus supplements). Also track your performance metric (like running time, weight lifted, or endurance) weekly to see if increased protein intake correlates with improvements.
  • If using the app to track supplements: Log each protein supplement dose with the time taken and total grams of protein. Also log your meals to see total daily protein and calories. This helps you understand whether you’re getting enough protein from food alone or if supplements are actually adding meaningful amounts. Set reminders to take supplements at consistent times if timing matters for your sport.
  • Over 8-12 weeks, track whether your athletic performance improves while maintaining consistent protein intake and total calories. Compare weeks where you hit your protein target versus weeks where you don’t. Also monitor how you feel during recovery—do you feel less sore or tired? Keep notes on whether the supplement seems worth the cost based on your actual results, not just the marketing claims.

This research summary is for educational purposes only and should not replace professional medical or nutritional advice. Individual responses to protein supplements vary based on age, health status, training intensity, and overall diet. Athletes with kidney disease, diabetes, or other health conditions should consult with a healthcare provider or registered dietitian before starting protein supplements. Pregnant or breastfeeding women should also seek professional guidance. While this meta-analysis provides evidence-based information, it does not constitute medical advice for your specific situation. Always talk to a qualified healthcare professional before making significant changes to your diet or supplement routine.