Are protein powders actually good for you? It's a fair question, and searching for an answer usually makes things worse. You'll find claims that protein powder wrecks your kidneys, that it's only for bodybuilders, that it has to be whey to work, and that it'll pack on fat if you're not careful. Somewhere underneath all that is what the research actually shows.
This post checks those five protein powder myths against the best evidence we have in 2026, not gym-floor opinion. By the end you'll know which claims hold up, which don't, and whether a protein powder genuinely fits your goals.
Myth 1: Protein Powder Is Bad for Your Health
The kidney and liver damage claim is probably the most common protein myth going. It comes from a real physiological fact: higher protein intake does increase your kidneys' workload in the short term. The leap to "this causes damage" is where the evidence stops agreeing.
A systematic review and meta-analysis by Devries et al. (2018) looked at kidney function markers across dozens of studies comparing higher- and lower-protein diets in healthy adults, and found no meaningful difference between groups. A separate one-year crossover trial in resistance-trained men by Antonio et al. (2016) tracked kidney and liver markers on a high-protein diet and found no adverse changes.
That's specific to people without existing kidney disease. If you have a diagnosed kidney or liver condition, protein intake is something to manage with your doctor, not a blog post.
Myth 2: Protein Powder Is Only Good for Building Muscle
Muscle gain gets all the marketing, but it's not the only thing protein does. Leidy et al. (2015) reviewed the evidence on protein and weight management and found that meals with 25 to 30g of protein improve satiety more than equivalent meals higher in carbs or fat, and that diets around 1.2 to 1.6g of protein per kg of body weight support fat loss while protecting lean mass during a calorie deficit. Long-term data is thinner than the short-term studies, and sticking to the higher protein target consistently matters more than the number itself.
In practice, that makes protein powder useful for anyone trying to hit a daily protein target without eating six chicken breasts, whether the goal is building muscle or lose body fat whilst maintaining the muscle you already have. Learn more in our blog Does Protein Powder Help Weight Loss? A Simple Guide (2026)
Myth 3: Only Whey Protein Actually Works
Whey digests fast and is rich in leucine, the amino acid that most directly triggers muscle protein synthesis, so it has a genuine edge in short-term lab studies. But short-term synthesis spikes aren't the same as long-term muscle gains.
Messina et al. (2018) ran a meta-analysis on nine studies involving 266 participants comparing soy protein supplementation against animal protein (including whey and dairy) during resistance training programs and found no significant difference in muscle mass or strength gains between the two. If you'd rather go plant-based, our guide to pea, soy, hemp and other plant proteins covers which sources come closest to whey and which fall short.
Myth 4: Protein Powder Isn't Good for Endurance Sports
Protein gets filed under "strength training only" a lot, which misses what it actually does for endurance athletes: repairing exercise-induced muscle damage and supporting metabolic flexibility in times of low carbohydrate intake.
A 2025 review by Witard et al. in Sports Medicine put endurance athletes' protein needs at roughly 1.8g per kg of body weight per day, about 50% higher than a sedentary adult and in the same range recommended for strength athletes, rising further on hard training days with limited carbohydrate availability. Runners, cyclists, hryox, and multi-sport athletes are leaving recovery on the table if they treat protein as a lifter-only concern.
Myth 5: Protein Powder Makes You Gain Fat
This one confuses protein with calories. Bray et al. (2012) deliberately overfed participants for eight weeks on diets containing 5%, 15% or 25% of calories from protein. Everyone gained roughly the same amount of fat regardless of protein level, because total calorie surplus drove the fat gain, not the protein itself. However, the higher-protein groups gained more lean mass than the lowest-protein group, plus had higher energy expenditure at rest.
A scoop of protein powder added on top of an already excessive calorie intake will contribute to weight gain, the same as any other food would. It isn't uniquely fattening, and within a sensible calorie budget it's one of the easier ways to protect muscle while losing fat.
The Bottom Line
Protein powder doesn't damage healthy kidneys, isn't limited to muscle-building, doesn't require whey specifically, and isn't fattening on its own. It also isn't just for lifters: endurance athletes have a real, evidence-backed case for using it too.
Ready to find the right fit? Browse our Protein Powder collection for whey and plant-based options backed by real nutrition information, not gym folklore.
References
Antonio, J., Ellerbroek, A., Silver, T., Vargas, L., Tamayo, A., Buehn, R., & Peacock, C. A. (2016). A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males. Journal of nutrition and metabolism, 2016, 9104792. https://doi.org/10.1155/2016/9104792
Bray, G. A., Smith, S. R., de Jonge, L., Xie, H., Rood, J., Martin, C. K., Most, M., Brock, C., Mancuso, S., & Redman, L. M. (2012). Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA, 307(1), 47–55. https://doi.org/10.1001/jama.2011.1918
Devries, M. C., Sithamparapillai, A., Brimble, K. S., Banfield, L., Morton, R. W., & Phillips, S. M. (2018). Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis. The Journal of nutrition, 148(11), 1760–1775. https://doi.org/10.1093/jn/nxy197
Leidy, H. J., Clifton, P. M., Astrup, A., Wycherley, T. P., Westerterp-Plantenga, M. S., Luscombe-Marsh, N. D., Woods, S. C., & Mattes, R. D. (2015). The role of protein in weight loss and maintenance. The American journal of clinical nutrition, 101(6), 1320S–1329S. https://doi.org/10.3945/ajcn.114.084038
Messina, M., Lynch, H., Dickinson, J. M., & Reed, K. E. (2018). No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. International journal of sport nutrition and exercise metabolism, 28(6), 674–685. https://doi.org/10.1123/ijsnem.2018-0071
Witard, O. C., Hearris, M., & Morgan, P. T. (2025). Protein Nutrition for Endurance Athletes: A Metabolic Focus on Promoting Recovery and Training Adaptation. Sports medicine (Auckland, N.Z.), 55(6), 1361–1376. https://doi.org/10.1007/s40279-025-02203-8
