Is the protein RDA too low to build muscle?

other primary study · 2020

“This meta-analysis revealed that total protein intake enhances the increase in LBM in a dose-dependent manner over a wide range of doses (0.5–3.5 g/kg BW).”

Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev
Who: healthy adults without serious illness (mean age 47, range 19-81) in RCTs varying protein intake, with or without resistance training
PMID 33300582

controlled trial · 2024

“We showed that increasing daily protein intake by ∼60% from the RDA level to ∼1.3 g/kg/d during the supplemental phase, much closer to suggested protein intakes for older adults, augmented integrated MPS rates by ∼10%.”

The effects of whey, pea, and collagen protein supplementation beyond the recommended dietary allowance on integrated myofibrillar protein synthetic rates in older males: a randomized controlled trial. Am J Clin Nutr
Who: Healthy older males aged 65-80 (mean 72) in Hamilton, Ontario, not resistance training
PMID 38762187

pooled analysis · 2018 · landmark

“Thus, consuming protein at the RDA of 0.8 g protein/kg/day appears insufficient for those who have the goal of gaining greater strength and FFM with RET.”

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. Br J Sports Med
Who: healthy, non-energy-restricted adults doing resistance training in RCTs (mean age 35±20; 10 studies in trained participants, 13 in adults >45)
PMID 28698222

pooled analysis · 2022 · landmark

“The results on older subjects seem marginal or influenced by individual studies.”

Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults. J Cachexia Sarcopenia Muscle
Who: Healthy non-obese adults aged 18+ (mean ages 19-85), untrained or trained, in RCTs of added protein with or without resistance exercise
PMID 35187864

controlled trial · 2017

“In conclusion, the lower than targeted protein intake of 1.13 g/kg/d obtained by consuming regular protein rich foods did not significantly affect FFM and FM change during modest weight loss in older overweight and obese subjects.”

Effect of a high protein diet and/or resistance exercise on the preservation of fat free mass during weight loss in overweight and obese older adults: a randomized controlled trial. Nutr J
Who: Overweight and obese adults aged 55 and over (mean 62.4 years) in a weight-loss program, Amsterdam
PMID 28166780

pooled analysis · 2022

“However, in interventions that did use RE, sub-group analysis revealed the change in ALM was statistically significantly greater in protein interventions compared with lower protein control groups (WMD: 0.54, 95% CI: 0.03, 1.05, I2: 89.76%) (Figure 3).”

Protein interventions augment the effect of resistance exercise on appendicular lean mass and handgrip strength in older adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr
Who: Older adults (mean age 61-85; healthy, frail, sarcopenic) in RCTs of protein supplementation or higher-protein diets with or without resistance exercise
PMID 34673936

controlled trial · 2018

“Protein intake equal to the RDA was sufficient to maintain LBM, muscle strength, and physical function in functionally limited older men.”

Effect of Protein Intake on Lean Body Mass in Functionally Limited Older Men: A Randomized Clinical Trial. JAMA Intern Med
Who: Community-dwelling functionally limited men aged 65+ (mean 73.0) with usual protein intake at or below 0.83 g/kg/d
PMID 29532075

systematic review · 2022

“The committee judged that the available evidence from human RCTs is not sufficiently convincing to state that increasing protein intake in older adults from the general population with a habitual protein intake of at least 0.8 g/(kg BW ⋅ d) would elicit health benefits.”

Health Effects of Increasing Protein Intake Above the Current Population Reference Intake in Older Adults: A Systematic Review of the Health Council of the Netherlands. Adv Nutr
Who: Older adults (sampling age >=50, mostly mean age >=65) from the general population with habitual protein intake >=0.8 g/kg/d, in RCTs
PMID 35016214

controlled trial · 2017

“In conclusion, the intake of higher amounts of protein (~1.2 g·kg −1 ·day −1 ) did not promote higher LBM gain when compared to the RDA (~0.8 g·kg −1 ·day −1 ) in postmenopausal women after resistance exercise protocol.”

Higher Protein Intake Does Not Improve Lean Mass Gain When Compared with RDA Recommendation in Postmenopausal Women Following Resistance Exercise Protocol: A Randomized Clinical Trial. Nutrients
Who: Sedentary postmenopausal women, Brazil
PMID 28895933

pooled analysis · 2018 · landmark

“Given that the CI of this estimate spanned from 1.03 to 2.20, it may be prudent to recommend ~2.2 g protein/kg/d for those seeking to maximise resistance training-induced gains in FFM.”

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. Br J Sports Med
Who: healthy, non-energy-restricted adults doing resistance training in RCTs (mean age 35±20)
PMID 28698222

pooled analysis · 2022 · landmark

“Alternatively, the evidence in this meta‐analysis supports the hypothesis that additional protein ingestion (1.6 g of protein/kg/day or higher) leads to small increments in lean body mass in studies enrolling young subjects in RE training.”

Systematic review and meta-analysis of protein intake to support muscle mass and function in healthy adults. J Cachexia Sarcopenia Muscle
Who: Healthy non-obese adults aged 18+ (mean ages 19-85), untrained or trained, in RCTs of added protein with or without resistance exercise
PMID 35187864

controlled trial · 2016

“Our results showed that, during a marked energy deficit, consumption of a diet containing 2.4 g protein · kg(-1) · d(-1) was more effective than consumption of a diet containing 1.2 g protein · kg(-1) · d(-1) in promoting increases in LBM and losses of fat mass when combined with a high volume of resistance and anaerobic exercise.”

Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr
Who: 40 overweight (BMI >25), recreationally active young men (23 ± 2 y) not regularly resistance training
PMID 26817506

other primary study · 2023

“With the exception of peak power, intake of 1.6 g.kg−1.d−1 of protein appears sufficient to maximize gains in lean mass, muscle strength, performance, and aerobic capacity during both RT and CT without influencing markers of kidney and liver function, indicating this daily protein amount is effective and safely tolerated in young, healthy adults.”

Effects of 16 weeks of two different high-protein diets with either resistance or concurrent training on body composition, muscular strength and performance, and markers of liver and kidney function in resistance-trained males. J Int Soc Sports Nutr
Who: Young healthy resistance-trained males aged 18-36 (mean 26 yr, BMI 25.6) in Isfahan, Iran
PMID 37516903

pooled analysis · 2012 · landmark

“Protein supplementation showed a positive effect for FFM (weighted mean difference: 0.69 kg; 95% CI: 0.47, 0.91 kg; P < 0.00001) and 1-RM leg press strength (weighted mean difference: 13.5 kg; 95% CI: 6.4, 20.7 kg; P < 0.005) compared with a placebo after prolonged resistance-type exercise training in younger and older subjects.”

Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. Am J Clin Nutr
Who: Healthy adults (>18 y, BMI <30) in RCTs of resistance training with protein supplementation; younger (mean 23 y) and older (mean 62 y) groups, trained and untrained
PMID 23134885

pooled analysis · 2020

“In a meta-analysis of 26 studies with 31 comparisons, there is moderate quality evidence that protein supplementation improved gains in LBM compared with the control group in both adults (MD: 0.62 kg; 95% CI: 0.36–0.88 kg, P < 0.00001, I2 = 0%) (Figure 1A) and older adults (MD: 0.46 kg; 95% CI: 0.23–0.70 kg, P = 0.0001, I2 = 0%) (Figure 1B).”

The Role of Protein Intake and its Timing on Body Composition and Muscle Function in Healthy Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Nutr
Who: Free-living healthy adults (mean age 18-55) and older adults (>55), incl. some obese, frail or sarcopenic, in RCTs of protein supplementation or high-protein diets, mostly with resistance training
PMID 32232404

controlled trial · 2015

“The main finding of the present study was that a higher protein intake does not cause a greater MM gain compared with normal intake (i.e., 1.8 g of protein·kg−1·day−1 vs. NP group 0.85 g of protein·kg−1·day−1) in healthy young subjects.”

Protein supplementation increases postexercise plasma myostatin concentration after 8 weeks of resistance training in young physically active subjects. J Med Food
Who: 18 healthy young male sports-science students (24.9 ± 5.3 years), physically active in team sports, untrained in resistance training
PMID 25133710