When it comes to building muscle, losing fat, or achieving the ultimate body recomposition, it goes without saying that adequate protein intake is paramount.
It provides the building blocks your muscles need (amino acids) to build and repair muscle tissue. But, that only begins to scratch the surface of the many functions of dietary protein and amino acids in the body.
Protein (and its constituent amino acids) are also necessary for:
- Hormone production
- Neurotransmitter synthesis
- Immune function
- Enzymatic activity
- Structural repairs (hair, skin, nails, etc.)
- Gut health
Despite the numerous vital roles that protein plays in the body, there are still many in the fitness and nutrition realms who are under the idea that high-protein diets are dangerous.
Today, we debunk 3 of the most common myths surrounding high-protein diets.
Let’s get started!
3 Common Myths About High-Protein Diets Debunked
#1 High Protein Diets Are Bad for Kidneys
The recommended daily allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day.
While this amount of protein may be enough for individuals that are not highly active and/or looking to build muscle and strength, it is woefully low for fitness enthusiasts looking to get substantial results from their diet and training program.
Still, when many individuals are advised to eat between 0.8-1 gram per pound of bodyweight (which is about two times the current RDA for protein) to maximize their results, they balk at the idea for fear that consuming so much protein may impair the function of their kidneys,
However, research is quite clear that in individuals with no pre-existing kidney issues, high protein diets are well-tolerated and pose no adverse risk.[1,2,3,4,5]
In fact, one particular study of note fed healthy, resistance-trained men a high protein diet, containing between 2.51–3.32 g/kg protein per day for an entire year and found no evidence of adverse effects on measures of blood lipids or liver and kidney function.[6]
Another study fed resistance-trained men a daily protein intake of 4.4g/kg (2g/lb) for eight weeks and observed no detrimental effects to kidney function.[7]
In case you were wondering, 4.4g/kg of bodyweight is approximately FIVE times the RDA for protein intake!
Recently, a 2019 systematic review found that high-protein diets were NOT associated with a reduction in kidney function and that long-term low protein intakes (<0.8 g/kg/day) may actuallyincrease risk of mortality.[8]
The takeaway here is that if you have no pre-existing kidney issues, there is no concern with eating a high-protein diet.
#2 High Protein Diets Leach Calcium from Bones
After being bad for your kidneys, the next most common myth surrounding high-protein diets is that they can potentially leach calcium from the bones.
The basis for this myth lies in the belief that protein increases the acidity of the blood. In order to prevent the blood from becoming too acidic, it must remove calcium from bone to neutralize the acid.
Long-term research finds that not only is bone health not threatened by high-protein diets, it may actually lead to improvements in several hormones that support bone health, including IGF-1.[9]
Moreover, other studies have found that higher protein intakes may[10,11,12,13]:
- Improve bone density
- Lower fracture risk
- Increase IGF-1 levels
- Enhance lean mass
Interestingly, all of these factors promote bone health, all of which serve to support bone health.
A 2018 review on high-protein diets and bone health conducted by the International Osteoporosis Foundation noted that[14]:
- Bone mineral density was positively associated with dietary protein intakes (meaning higher protein intakes are linked with higher bone mineral density)
- Higher protein intakes were linked to a modestly reduced risk of hip fracture, provided that calcium intake is sufficient
- Dairy products, which combine protein and calcium, beneficially impact bone turnover markers and bone mineral density
- No direct evidence was found between the acid load of high protein intakes and the progression of osteoporosis, reduced bone strength, or fractures.
Researchers concluded the review by stating:
“With intakes above the current RDA, dietary protein is rather beneficial in reducing bone loss and fracture risk, especially at the hip, provided calcium intakes are adequate. Insufficient dietary protein intakes may be a much more severe problem than protein excess.”[14]
Suffice it to say that this myth is busted!
#3 High Protein Diets Cause Fat Gain
This myth is a bit mind-boggling as protein is the most anabolic macronutrient of all -- it literally helps build and repair muscle tissue.
Yet somehow, a myth permeates that high protein diets cause fat gain.
Let us be clear, no single macronutrient will cause you to gain fat (no even carbohydrates).
An abundance (excess) of calories will cause fat gain. It’s that simple.
Protein is highly satiating, which makes it very filling and difficult to overconsume. Furthermore, the body has to work incredibly hard to convert protein into fat. As it must first be broken down into amino acids, then converted to glucose. If the glucose molecules aren’t needed, then they are converted into fatty acids and stored in adipose tissue.
As you can see, it’s incredibly difficult for the body to actually store protein as fat.
To top it off, numerous studies have shown that not only are high protein diets superior for weight loss, but they’re also more effective for maintaining weight loss after a diet is complete.[15,16,17]
Takeaway
High-protein diets have gotten a bad rap over the years.
In otherwise healthy individuals, high-protein diets do NOT hurt kidney function, cause fat gain, or leach calcium from bones.
High protein diet do help build muscle, support immune function, improve recovery, and boost weight loss.
For active individuals looking to optimize their protein intake, current recommendations are to consume between 0.8-1.2 grams per pound of bodyweight per day.
References
- Friedman AN, Ogden LG, Foster GD, Klein S, Stein R, Miller B, Hill JO, Brill C, Bailer B, Rosenbaum DR, Wyatt HR:Comparative effects of low-carbohydrate high-protein versus low-fat diets on the kidney. Clin J Am Soc Nephrol 2012, 7:1103-1111.
- Poortmans JR, Dellalieux O: Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sport Nutr Exerc Metab 2000, 10:28-38.
- Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T: The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr 2014, 11:19
- Devries MC, Sithamparapillai A, Brimble KS, Banfield L, Morton RW, Phillips SM. 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. J Nutr. 2018;148(11):1760-1775.
- F Martin, W., Armstrong, L., & Rodriguez, N. (2005). Dietary Protein Intake and Renal Function. Nutrition & Metabolism(Vol. 2). https://doi.org/10.1186/1743-7075-2-25
- Jose Antonio, Anya Ellerbroek, Tobin Silver, et al., “A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males,” Journal of Nutrition and Metabolism, vol. 2016, Article ID 9104792, 5 pages, 2016. https://doi.org/10.1155/2016/9104792.
- Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T: The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. J Int Soc Sports Nutr 2014, 11:19
- Bilancio, Giancarlo, et al. "Dietary Protein, Kidney Function and Mortality: Review of the Evidence from Epidemiological Studies." Nutrients, vol. 11, no. 1, 2019, p. 196.
- Dawson-Hughes, B., Harris, S. S., Rasmussen, H., Song, L., & Dallal, G. E. (2004). Effect of dietary protein supplements on calcium excretion in healthy older men and women. The Journal of Clinical Endocrinology and Metabolism, 89(3), 1169–1173. https://doi.org/10.1210/jc.2003-031466
- Rapuri PB , et al. "Protein Intake: Effects on Bone Mineral Density and the Rate of Bone Loss in Elderly Women. - PubMed - NCBI." National Center for Biotechnology Information, www.ncbi.nlm.nih.gov/pubmed/12791633.
- Fung TT , et al. "Protein Intake and Risk of Hip Fractures in Postmenopausal Women and Men Age 50 and Older. - PubMed - NCBI." National Center for Biotechnology Information, www.ncbi.nlm.nih.gov/pubmed/28074249.
- Levine ME , et al. "Low Protein Intake is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population. - PubMed - NCBI." National Center for Biotechnology Information, www.ncbi.nlm.nih.gov/pubmed/24606898.
- Sahni S , et al. "Higher Protein Intake Is Associated with Higher Lean Mass and Quadriceps Muscle Strength in Adult Men and Women. - PubMed - NCBI." National Center for Biotechnology Information,www.ncbi.nlm.nih.gov/pubmed/26019246.
- Rizzoli, R., Biver, E., Bonjour, JP. et al. Benefits and safety of dietary protein for bone health—an expert consensus paper endorsed by the European Society for Clinical and Economical Aspects of Osteopororosis, Osteoarthritis, and Musculoskeletal Diseases and by the International Osteoporosis Foundation. Osteoporos Int (2018) 29: 1933. https://doi.org/10.1007/s00198-018-4534-5
- Kim JE, O'Connor LE, Sands LP, Slebodnik MB, Campbell WW. Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis. Nutr Rev. 2016;74(3):210-224. doi:10.1093/nutrit/nuv065
- Pasiakos SM, Cao JJ, Margolis LM, et al. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: a randomized controlled trial. FASEB J. 2013;27(9):3837-3847. doi:10.1096/fj.13-230227
- Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression 1. Am J Clin Nutr. 2006;83(2):260-274. doi:10.1093/ajcn/83.2.260
