How much protein do I need per day?
Strong EvidenceYES
Strong evidence: Most adults need 0.8g/kg body weight minimum. For muscle building, 1.6-2.2g/kg is optimal. Athletes and older adults benefit from the higher end. More than 2.2g/kg shows no additional muscle benefit.
The Verdict
Strong evidence: Most adults need 0.8g/kg body weight minimum. For muscle building, 1.6-2.2g/kg is optimal. Athletes and older adults benefit from the higher end. More than 2.2g/kg shows no additional muscle benefit.
What the Evidence Shows
Protein requirements vary based on age, activity level, and goals. The RDA of 0.8g/kg body weight (about 55g for a 150lb person) is the minimum to prevent deficiency in sedentary adults. However, this is inadequate for muscle building, athletic performance, or healthy aging. Multiple meta-analyses show that for maximizing muscle protein synthesis and strength gains, 1.6-2.2g/kg body weight is optimal. A landmark 2018 meta-analysis of 49 studies found that protein intakes above 1.6g/kg provided additional benefits for muscle mass, but gains plateaued beyond 2.2g/kg. Older adults (65+) may need higher protein (1.0-1.2g/kg minimum) to offset anabolic resistance. During weight loss, higher protein (2.0-2.4g/kg) helps preserve muscle. Protein timing matters less than total daily intake — the 'anabolic window' is overstated. For most people, 1.6g/kg (0.7g/lb) is a practical target that balances muscle benefits with dietary flexibility.
Evidence Quality
8
Meta-Analyses
45
RCTs
30
Observational
Important Caveats
- ⚠️ Individual needs vary based on age, activity, body composition goals, and health status
- ⚠️ Older adults (65+) have higher requirements (1.0-1.2g/kg minimum) due to anabolic resistance
- ⚠️ During caloric deficit, protein needs increase (2.0-2.4g/kg) to preserve muscle
- ⚠️ Quality matters — complete proteins with all essential amino acids are preferred
- ⚠️ Very high protein diets (>3g/kg) may stress kidneys in people with pre-existing kidney disease
- ⚠️ Protein timing is less important than total daily intake
Population Studied
Healthy adults, athletes, resistance trainees, older adults. Meta-analyses cover thousands of participants across age groups and training statuses
Dosage
Minimum: 0.8g/kg body weight. Optimal for muscle: 1.6-2.2g/kg. Older adults: 1.0-1.2g/kg minimum. Weight loss: 2.0-2.4g/kg
Duration
Consistent daily intake matters more than single-day variation. Muscle protein synthesis is maximized over weeks to months
Supporting Studies (3)
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength
Meta-AnalysisMorton RW, Murphy KT, McKellar SR, et al. · British Journal of Sports Medicine (2018)
Meta-analysis of 49 studies (1863 participants) found protein supplementation significantly augments muscle mass and strength gains. Benefits plateau at ~1.6g/kg/day, with no additional benefit above 2.2g/kg.
View paper (DOI) →Dietary protein for athletes: From requirements to optimum adaptation
Meta-AnalysisPhillips SM, Van Loon LJ. · Journal of Sports Sciences (2011)
Comprehensive review concluded athletes benefit from 1.3-1.8g/kg, with endurance athletes at lower end and strength athletes at higher end.
View paper (DOI) →Evidence-based recommendations for protein intake in older adults
Meta-AnalysisBauer J, Biolo G, Cederholm T, et al. · Journal of the American Medical Directors Association (2013)
International consensus that older adults need 1.0-1.2g/kg minimum (vs 0.8g/kg RDA) due to anabolic resistance. Higher intake (1.2-1.5g/kg) recommended for those with chronic disease.
View paper (DOI) →Contradicting Studies (1)
Controversy over optimal protein intake for resistance training
ObservationalTipton KD, Witard OC. · Nutrition Reviews (2022)
While 1.6g/kg is often cited as optimal, individual variation is substantial. Some may benefit from higher intakes, while others show maximal response at lower doses.
Why this disagrees:
Highlights that population averages may not apply to individuals — some people may need more or less protein than the 1.6g/kg benchmark.
Related Claims
Are high-protein diets safe for kidney function in healthy people?
Moderate EvidenceModerate evidence that high-protein diets (>1.5g/kg/day) are safe for kidney function in healthy individuals with normal renal function. GFR increases adaptively but this is not pathological. However, high protein may accelerate decline in people with pre-existing chronic kidney disease. The distinction between healthy and compromised kidneys is critical.
Does protein intake above the RDA benefit muscle growth?
Strong EvidenceStrong evidence shows protein intake of 1.6-2.2g/kg/day optimizes muscle protein synthesis and hypertrophy, significantly above the RDA of 0.8g/kg/day. Benefits plateau around 1.6g/kg in most populations.
Does protein before bed improve muscle recovery?
Moderate EvidenceModerate evidence supports that consuming 30-40g of protein (particularly casein) before sleep enhances overnight muscle protein synthesis and recovery. Benefits are most consistent in resistance-trained individuals performing evening exercise.
Does protein timing matter for muscle growth?
Weak EvidenceThe 'anabolic window' concept — needing protein within 30-60 minutes of training — is largely overstated. Total daily protein intake and distribution across meals matters far more than precise post-workout timing.
💊 Related Supplements
Acetyl-L-Carnitine
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View supplement →Blueberries
Promising for cognitive health in aging adults with good antioxidant evidence, but effects are modest and not yet conclusive enough for a confident recommendation.
View supplement →Casein Protein
The best protein choice for before bed — slow digestion provides overnight amino acid delivery for muscle recovery.
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