For young men who already eat enough protein (about 1.3-1.4 grams per kilogram of body weight each day), taking extra protein supplements doesn't help them build more muscle or get stronger from weight training. This means the total amount of protein you eat each day matters more than where it comes from.
See the scientific wording
In young men with a habitual protein intake of 1.3-1.4 g/kg/day, additional protein supplementation does not enhance muscle mass or strength gains from resistance training, indicating that total daily protein intake is more important than protein source.
Indication only — weak evidence
Randomized trialsOne low-scoring study points this way, but the evidence is still early.
What the research says
1 study reviewedSupporting (1)
Randomized Controlled TrialHuman2023
The study found no differences between groups, and the authors interpret this as evidence that when total protein intake is sufficient, the source of additional protein does not matter, supporting the claim that total intake is the key factor.
Contradicting (0)
No contradicting studies found yet
That doesn't mean it's settled — it just means no study has tested the opposite.
Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.
Scores reflect study quality, not just count.
When you lift weights, your muscles get signals to build more protein. If you already eat enough protein, your muscles are already building as much as they can. Adding extra protein doesn't make them build more, because they are already full. So the type of protein doesn't matter if you get enough total protein.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting study
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For young men who already eat enough protein (about 1.3-1.4 grams per kilogram of body weight each day), taking extra protein supplements doesn't help them build more muscle or get stronger from weight training. This means the total amount of protein you eat each day matters more than where it comes from.
Mechanism
1 studyYour muscles grow when you exercise and eat enough protein. If you already eat enough protein, your muscles are already working at full speed. Adding more protein doesn't help, and it doesn't matter if it comes from plants or animals. So the key is getting enough total protein, not the type.
When you lift weights, your muscles get signals to build more protein. If you already eat enough protein, your muscles are already building as much as they can. Adding extra protein doesn't make them build more, because they are already full. So the type of protein doesn't matter if you get enough total protein.
Resistance exercise creates mechanical tension in muscle fibers, which activates the mTORC1 signaling pathway, increasing the rate of muscle protein synthesis.
Amino acids from dietary protein, especially leucine, are transported into muscle cells and further stimulate mTORC1, but this stimulation reaches a maximum when amino acid levels are already high.
When daily protein intake is already sufficient (≥1.2 g/kg body weight), the muscle is in a 'muscle full' state, meaning the anabolic response to additional protein is blunted, regardless of the protein source.
Over weeks of training, the combination of the training stimulus and adequate baseline protein intake results in net muscle protein accretion, leading to increases in muscle mass and strength, but additional protein supplementation does not augment this process.
Evidence from Studies
Supporting (1)
Community contributions welcome
Contradicting (0)
Community contributions welcome
Score Breakdown
No multi-axis breakdown available yet. The overall Pro / Against score above is the best signal.
- No clinical evidence is available; the score reflects mechanistic plausibility only.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Systematic Review and Meta-Analysis of Protein Supplementation on Muscle Mass and Strength in Young Men with Adequate Habitual Protein Intake
A comprehensive search of RCTs comparing protein supplementation vs placebo in young men (18-35 years) with habitual protein intake ≥1.3 g/kg/day, undergoing resistance training for at least 8 weeks, measuring changes in lean body mass and strength.
Double-Blind Randomized Controlled Trial of Protein Supplementation vs Placebo in Young Men with Habitual Protein Intake 1.3-1.4 g/kg/day During Resistance Training
Randomized, double-blind, placebo-controlled trial with 100+ young men (18-35 years) with habitual protein intake 1.3-1.4 g/kg/day, assigned to receive either a protein supplement (e.g., whey) or an isocaloric placebo, both groups performing the same resistance training program for 12 weeks, measuring changes in lean body mass via DXA and strength via 1RM tests.
Prospective Cohort Study of Protein Supplement Use and Muscle Mass/Strength in Young Men with Habitual Protein Intake 1.3-1.4 g/kg/day
Prospective cohort of 500+ young men (18-35 years) with habitual protein intake 1.3-1.4 g/kg/day, following them for 1 year, recording protein supplement use, resistance training frequency, and measuring muscle mass and strength at baseline and follow-up, adjusting for confounders like total energy intake and training volume.
Cross-Sectional Analysis of Protein Supplement Use and Muscle Mass/Strength in Young Men with Habitual Protein Intake 1.3-1.4 g/kg/day
A cross-sectional survey and body composition assessment of 1000 young men (18-35 years) with habitual protein intake 1.3-1.4 g/kg/day, collecting data on protein supplement use, resistance training history, and measuring muscle mass via BIA and strength via handgrip or leg press, using regression to adjust for confounders.