Most people know that eating a high-protein diet benefits your health in many ways, including helping you build and maintain muscle, lose fat, and live a long, healthy life.
That said, the idea that high-protein dieting is bad for your kidneys has been kicking around for decades, making many people wonder if the benefits are worth the risks.
Is too much protein bad for your kidneys, though?
Learn what science says in this article.
(Or if you’d prefer to skip all of the scientific mumbo jumbo and you just want to know how much of each macronutrient, how many calories, and which foods you should eat to lose weight, no problem! Just take the Legion Diet Quiz, and in less than a minute, you’ll know exactly what diet is right for you. Click here to check it out.)
What Is Protein?
A protein is a large molecule made up of chains of smaller compounds known as amino acids.
You can think of amino acids as the “building blocks” of many tissues in the body, including muscle, hair, nails, and skin.
Your body is able to synthesize 12 amino acids it needs but must obtain the final 9 from the food you eat. This is why you must eat protein to survive.
Why Do People Think Protein Is Bad for Your Kidneys?
Your kidneys perform a number of functions, including filtering your blood to get rid of waste products, regulating blood pressure by changing your water and sodium balance, maintaining a healthy blood pH level, and creating certain hormones.
When your body metabolizes protein, it creates a substance called urea, which your kidneys remove from your blood and then flush out through your urine. The more protein you eat, the more urea your kidneys have to remove from your blood.
Some people say that this increased urea production from high-protein dieting puts more wear and tear on your kidneys, damaging them over time.
Is Too Much Protein Bad for Your Kidneys?
A couple of long-term observational studies have shown that there’s an association between high-protein dieting and declining kidney function, particularly among people with kidney disease. Some animal research also shows that high-protein dieting may increase the likelihood of experiencing renal (kidney) issues.
However, observational studies can only show that two things are associated, not that one causes the other, and animal research has limited applicability to humans. In other words, while there’s some evidence that high-protein dieting might be no bueno for rodents and humans with kidney disease, there’s very little evidence it’s harmful for healthy people.
If we look at higher-quality evidence, such as randomized-controlled trials, virtually all show that high-protein dieting has no negative effect on kidney function in people who have healthy kidneys.
For example, a study conducted by the Free University of Brussels investigated bodybuilders and other well-trained athletes with above-average protein intake (up to ~1.3 grams per pound of body weight per day). After seven days of dietary analysis and blood work, researchers found no evidence of kidney distress.
These results were replicated by scientists at The University of Ulm, who investigated chronic protein intake on kidney function in 88 healthy volunteers, including vegetarians and bodybuilders, with protein intake as high as ~1.2 grams per pound of body weight per day (around three times the Recommended Daily Allowance). After four months, there were no signs of negative changes in kidney function.
Several similar studies conducted by a team of researchers at Nova Southeastern University investigating protein intakes as high as ~1.5-to-2 grams per pound of body weight per day have also consistently reported that protein has no adverse effects on health whatsoever.
Finally, the 2003 Nurses’ Health Study conducted by Harvard Medical School supports these findings, too. After analyzing the protein intake of 1,624 women over the course of several years, researchers found no association between high protein intake and a decline in kidney function in healthy females.
The reason for this is simple: while your kidneys do have to work a tad harder to remove the urea produced by metabolizing large amounts of protein, it’s still well within their capabilities.
Think of it this way: Drinking more water also forces your kidneys to work harder, but you don’t hear anyone saying you should drink less to protect your kidneys (although hydration in general is a bit overhyped). The reason for this is that, like drinking lots of water, eating lots of protein is also entirely natural and something your kidneys are well-equipped to handle.
Thus, saying that eating a high-protein diet “stresses” your kidneys is like saying that charging your phone “stresses” the electrical grid, or that taking a shower “stresses” your home’s plumbing system.
In the big scheme of things, it’s a drop in the bucket.
How Much Protein Do You Need?
Protein needs vary from individual to individual.
The Institute of Medicine recommends that sedentary people aged 17-to-90 years old eat at least ~0.4 grams of protein per pound of body weight per day to avoid losing muscle and stave off decrepitude (though eating more is likely better if you want to flourish instead of just survive).
If you’re physically active (particularly if you regularly lift weights), you need to eat more than this to repair and build new tissue, though the exact amount is the subject of ongoing debate among scientists and depends on your body composition goals.
(If you’d like to know exactly how much protein you should eat for your goals, take the Legion Diet Quiz.)
How Much Protein Do You Need While Cutting?
While restricting your calorie intake to lose weight, your body doesn’t have an excess of calories to use as fuel. Since your fat and glycogen stores are also likely depleted, your body is primed to use muscle as a source of energy. Eating protein prevents this, so it makes sense to increase your intake while cutting.
A 2018 review published in the International Journal of Sport Nutrition and Exercise Metabolism recommends that people trying to lose weight and preserve muscle consume 0.8-to-1.1 grams per pound of body weight.
Another systematic review conducted by scientists at AUT University found that eating slightly more protein—0.8-to-1.2 grams per pound of body weight—might be better.
And yet another review suggested an even higher protein intake: 1-to-1.5 grams per pound of body weight per day. That said, the higher end of that range isn’t necessary unless you’re lean and muscular and working to get very lean (a bodybuilder preparing for a show, for instance).
Thus, a sensible target while cutting (and the one I advocate in my fitness books for men and women, Bigger Leaner Stronger and Thinner Leaner Stronger), is 1-to-1.2 grams of protein per pound of body weight per day.
How Much Protein Do You Need While Maintaining and Bulking?
While maintaining your weight or bulking, you can take your foot off the gas a little regarding protein because your body is unlikely to use muscle for fuel when it has an abundance of calories.
The results of a meta-analysis conducted by scientists at McMaster University that examined data from 49 studies, including 1,863 participants, showed that a good rule of thumb when “not energy restricted” is 0.7-to-1 gram per pound of body weight per day. The authors also noted that leaning toward the top end of this scale likely maximizes muscle growth.
Another review published in the Journal of the International Society of Sports Nutrition explained that 0.55-to-1 gram of protein per pound of body weight per day is adequate for supporting muscle gain so long as calories are at or above expenditure (maintenance or bulking).
Since eating toward the top end of these ranges likely maximizes muscle growth and minimizes fat gain, I think it’s sensible to do so, which is why I recommend 0.8-to-1 gram of protein per pound of body weight per day while maintaining or bulking.
FAQ #1: Is protein bad for your kidneys?
No, research shows that consuming a high-protein diet isn’t bad for your kidneys unless you already have a pre-existing kidney condition.
FAQ #2: What’s the connection between protein and kidney disease?
Some observational research shows that increased protein intake is associated with the progression of kidney disease.
However, most high-quality research shows that consuming a high-protein diet has no adverse effects on kidney function, provided you don’t have any pre-existing kidney problems. If you do have impaired kidney function, talk to your doctor about how much protein is safe for you to consume.
FAQ #3: Does whey protein cause kidney stones?
There’s an idea floating around that protein from any source, including whey, causes kidney stones, but the results of two reviews show there’s insufficient evidence to draw any conclusions. In other words, there’s currently no proof this is the case, and it’s probably not worth worrying about.
+ Scientific References
- Watford, M., & Wu, G. (2018). Protein. Advances in Nutrition, 9(5), 651. https://doi.org/10.1093/ADVANCES/NMY027
- Ogobuiro I, T. F. (n.d.). Physiology, Renal – StatPearls – NCBI Bookshelf. Retrieved June 13, 2022, from https://www.ncbi.nlm.nih.gov/books/NBK538339/
- Sahay, M., Kalra, S., & Bandgar, T. (2012). Renal endocrinology: The new frontier. Indian Journal of Endocrinology and Metabolism, 16(2), 154. https://doi.org/10.4103/2230-8210.93729
- Weiner, I. D., Mitch, W. E., & Sands, J. M. (2015). Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion. Clinical Journal of the American Society of Nephrology : CJASN, 10(8), 1444–1458. https://doi.org/10.2215/CJN.10311013
- Cirillo, M., Lombardi, C., Chiricone, D., De Santo, N. G., Zanchetti, A., & Bilancio, G. (2014). Protein intake and kidney function in the middle-age population: contrast between cross-sectional and longitudinal data. Nephrology, Dialysis, Transplantation : Official Publication of the European Dialysis and Transplant Association – European Renal Association, 29(9), 1733–1740. https://doi.org/10.1093/NDT/GFU056
- Farhadnejad, H., Asghari, G., Emamat, H., Mirmiran, P., & Azizi, F. (2019). Low-Carbohydrate High-Protein Diet is Associated With Increased Risk of Incident Chronic Kidney Diseases Among Tehranian Adults. Journal of Renal Nutrition : The Official Journal of the Council on Renal Nutrition of the National Kidney Foundation, 29(4), 343–349. https://doi.org/10.1053/J.JRN.2018.10.007
- Granqvist, A. B., Ericsson, A., Sanchez, J., Tonelius, P., William-Olsson, L., Dahlqvist, U., Andersson, A. K., Tomic, T. T., Hudkins, K., Alpers, C. E., Pellegrini, G., & Söderberg, M. (2020). High protein diet accelerates diabetes and kidney disease in the BTBR ob/ob mouse. American Journal of Physiology – Renal Physiology, 318(3), F763–F771. https://doi.org/10.1152/AJPRENAL.00484.2019/ASSET/IMAGES/LARGE/ZH20032090280008.JPEG
- Tovar-Palacio, C., Tovar, A. R., Torres, N., Cruz, C., Hernández-Pando, R., Salas-Garrido, G., Pedraza-Chaverri, J., & Correa-Rotter, R. (2011). Proinflammatory gene expression and renal lipogenesis are modulated by dietary protein content in obese Zucker fa/fa rats. American Journal of Physiology. Renal Physiology, 300(1). https://doi.org/10.1152/AJPRENAL.00171.2010
- Møller, G., Andersen, J. R., Ritz, C., Silvestre, M. P., Navas-Carretero, S., Jalo, E., Christensen, P., Simpson, E., Taylor, M., Martinez, J. A., Macdonald, I., Swindell, N., Mackintosh, K. A., Stratton, G., Fogelholm, M., Larsen, T. M., Poppitt, S. D., Dragsted, L. O., & Raben, A. (2018). Higher Protein Intake Is Not Associated with Decreased Kidney Function in Pre-Diabetic Older Adults Following a One-Year Intervention-A Preview Sub-Study. Nutrients, 10(1). https://doi.org/10.3390/NU10010054
- Flechtner-Mors, M., Boehm, B. O., Wittmann, R., Thoma, U., & Ditschuneit, H. H. (2010). Enhanced weight loss with protein-enriched meal replacements in subjects with the metabolic syndrome. Diabetes/Metabolism Research and Reviews, 26(5), 393–405. https://doi.org/10.1002/DMRR.1097
- Li, Z., Treyzon, L., Chen, S., Yan, E., Thames, G., & Carpenter, C. L. (2010). Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial. Nutrition Journal, 9(1). https://doi.org/10.1186/1475-2891-9-72
- Wycherley, T. P., Brinkworth, G. D., Clifton, P. M., & Noakes, M. (2012). Comparison of the effects of 52 weeks weight loss with either a high-protein or high-carbohydrate diet on body composition and cardiometabolic risk factors in overweight and obese males. Nutrition & Diabetes, 2(8), e40. https://doi.org/10.1038/NUTD.2012.11
- Larsen, R. N., Mann, N. J., Maclean, E., & Shaw, J. E. (2011). The effect of high-protein, low-carbohydrate diets in the treatment of type 2 diabetes: a 12 month randomised controlled trial. Diabetologia, 54(4), 731–740. https://doi.org/10.1007/S00125-010-2027-Y
- Krebs, J. D., Elley, C. R., Parry-Strong, A., Lunt, H., Drury, P. L., Bell, D. A., Robinson, E., Moyes, S. A., & Mann, J. I. (2012). The Diabetes Excess Weight Loss (DEWL) Trial: a randomised controlled trial of high-protein versus high-carbohydrate diets over 2 years in type 2 diabetes. Diabetologia, 55(4), 905–914. https://doi.org/10.1007/S00125-012-2461-0
- Friedman, A. N., Ogden, L. G., Foster, G. D., Klein, S., Stein, R., Miller, B., Hill, J. O., Brill, C., Bailer, B., Rosenbaum, D. R., & Wyatt, H. R. (2012). Comparative effects of low-carbohydrate high-protein versus low-fat diets on the kidney. Clinical Journal of the American Society of Nephrology : CJASN, 7(7), 1103–1111. https://doi.org/10.2215/CJN.11741111
- Tirosh, A., Golan, R., Harman-Boehm, I., Henkin, Y., Schwarzfuchs, D., Rudich, A., Kovsan, J., Fiedler, G. M., Blüher, M., Stumvoll, M., Thiery, J., Stampfer, M. J., & Shai, I. (2013). Renal function following three distinct weight loss dietary strategies during 2 years of a randomized controlled trial. Diabetes Care, 36(8), 2225–2232. https://doi.org/10.2337/DC12-1846/-/DC1
- Tay, J., Thompson, C. H., Luscombe-Marsh, N. D., Noakes, M., Buckley, J. D., Wittert, G. A., & Brinkworth, G. D. (2015). Long-Term Effects of a Very Low Carbohydrate Compared With a High Carbohydrate Diet on Renal Function in Individuals With Type 2 Diabetes: A Randomized Trial. Medicine, 94(47), e2181. https://doi.org/10.1097/MD.0000000000002181
- Poortmans, J. R., & Dellalieux, O. (2000). Do regular high protein diets have potential health risks on kidney function in athletes? International Journal of Sport Nutrition and Exercise Metabolism, 10(1), 28–38. https://doi.org/10.1123/IJSNEM.10.1.28
- Frank, H., Graf, J., Amann-Gassner, U., Bratke, R., Daniel, H., Heemann, U., & Hauner, H. (2009). Effect of short-term high-protein compared with normal-protein diets on renal hemodynamics and associated variables in healthy young men. American Journal of Clinical Nutrition, 90(6), 1509–1516. https://doi.org/10.3945/ajcn.2009.27601
- Antonio, J., Ellerbroek, A., Silver, T., Vargas, L., & Peacock, C. (2016). The effects of a high protein diet on indices of health and body composition–a crossover trial in resistance-trained men. Journal of the International Society of Sports Nutrition, 13(1). https://doi.org/10.1186/S12970-016-0114-2
- Antonio, J., Peacock, C. A., Ellerbroek, A., Fromhoff, B., & Silver, T. (2014). The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Journal of the International Society of Sports Nutrition, 11(1). https://doi.org/10.1186/1550-2783-11-19
- 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. https://doi.org/10.1155/2016/9104792
- Antonio, J., Ellerbroek, A., Silver, T., Orris, S., Scheiner, M., Gonzalez, A., & Peacock, C. A. (2015). A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women–a follow-up investigation. Journal of the International Society of Sports Nutrition, 12(1). https://doi.org/10.1186/S12970-015-0100-0
- Knight, E. L., Stampfer, M. J., Hankinson, S. E., Spiegelman, D., & Curhan, G. C. (2003). The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency. Annals of Internal Medicine, 138(6). https://doi.org/10.7326/0003-4819-138-6-200303180-00009
- Trumbo, P., Schlicker, S., Yates, A. A., & Poos, M. (2002). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. Journal of the American Dietetic Association, 102(11), 1621–1630. https://doi.org/10.1016/S0002-8223(02)90346-9
- Metter, E. J., Talbot, L. A., Schrager, M., & Conwit, R. (2002). Skeletal muscle strength as a predictor of all-cause mortality in healthy men. The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences, 57(10), B359–B365. https://doi.org/10.1093/GERONA/57.10.B359
- Paddon-Jones, D., Short, K. R., Campbell, W. W., Volpi, E., & Wolfe, R. R. (2008). Role of dietary protein in the sarcopenia of aging. The American Journal of Clinical Nutrition, 87(5). https://doi.org/10.1093/AJCN/87.5.1562S
- Soenen, S., Martens, E. A. P., Hochstenbach-waelen, A., Lemmens, S. G. T., & Westerterp-plantenga, M. S. (2013). Normal protein intake is required for body weight loss and weight maintenance, and elevated protein intake for additional preservation of resting energy expenditure and fat free mass. The Journal of Nutrition, 143(5), 591–596. https://doi.org/10.3945/JN.112.167593
- Phillips, S. M., & van Loon, L. J. C. (2011). Dietary protein for athletes: from requirements to optimum adaptation. Journal of Sports Sciences, 29 Suppl 1(SUPPL. 1). https://doi.org/10.1080/02640414.2011.619204
- Hector, A. J., & Phillips, S. M. (2018). Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance. International Journal of Sport Nutrition and Exercise Metabolism, 28(2), 170–177. https://doi.org/10.1123/IJSNEM.2017-0273
- Helms, E. R., Zinn, C., Rowlands, D. S., & Brown, S. R. (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. International Journal of Sport Nutrition and Exercise Metabolism, 24(2), 127–138. https://doi.org/10.1123/IJSNEM.2013-0054
- Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52(6), 376–384. https://doi.org/10.1136/BJSPORTS-2017-097608
- van Elswyk, M. E., Weatherford, C. A., & McNeill, S. H. (2018). A Systematic Review of Renal Health in Healthy Individuals Associated with Protein Intake above the US Recommended Daily Allowance in Randomized Controlled Trials and Observational Studies. Advances in Nutrition (Bethesda, Md.), 9(4), 404–418. https://doi.org/10.1093/ADVANCES/NMY026