The Claim

In resistance-trained men participating in a 9-week resistance training program, consuming 20g of post-exercise protein with different ratios of fast-digested (whey) and slow-digested (casein) milk proteins—specifically 100% whey, 50% whey/50% casein, or 20% whey/80% casein—leads to comparable increases in lean body mass, dynamic strength, and isometric strength, despite differing plasma amino acid responses.

Source: Effects of Postexercise Protein Intake on Muscle Mass and Strength During Resistance Training: Is There an Optimal Ratio Between Fast and Slow Proteins?

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
38score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

If you're a guy who lifts weights, drinking a protein shake after your workout with different mixes of fast- and slow-digesting milk proteins — like whey and casein — gives you about the same muscle and strength gains, even if your body processes the amino acids differently.

See the scientific wording

In resistance-trained men undergoing a 9-week resistance training program, consuming 20g of post-exercise protein with varying ratios of fast-digested (whey) and slow-digested (casein) milk proteins—specifically 100% fast, 50% fast/50% slow, or 20% fast/80% slow—results in similar increases in lean body mass, dynamic strength, and isometric strength, despite differences in plasma amino acid response.

What the research says

1 study
  1. Study: Effects of Postexercise Protein Intake on Muscle Mass and Strength During Resistance Training: Is There an Optimal Ratio Between Fast and Slow Proteins?

    The study found that even though different protein mixes caused different spikes in amino acids, all groups gained the same amount of muscle and strength over time.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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