Research

Hormonal

Higher protein quality (specifically higher leucine content and digestibility, measured by DIAAS) promotes greater resistance exercise-induced muscle hypertrophy compared to lower quality proteins when protein doses are not artificially elevated to saturation.

To maximize muscle growth from resistance training, prioritize high-quality proteins rich in leucine (like whey, eggs, or meat) over lower-quality sources (like some plant proteins) unless you are willing to consume significantly larger amounts of the lower-quality protein to hit the same leucine threshold. This is particularly important for older adults who need higher leucine doses to stimulate muscle synthesis.

ModerateSupportsMEDIUM confidence
The leucine content of a protein is the strongest determinant of the capacity of a protein to affect MPS and likely hypertrophy... the importance of leucine content for MPS and likely subsequent hypertrophy needs to be appreciated in the context of not only its content in a protein source but also its digestibility.
Stuart M. Phillips · Nutrition & Metabolism · 2016

Why this rating

The paper is a review of mixed evidence; some studies show clear differences (whey vs soy), while others show equivalence when doses are matched/saturated.

Source

The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass

Stuart M. Phillips · Nutrition & Metabolism · 2016

DOI 10.1186/s12986-016-0124-8

narrative_reviewCited 163×
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DOI resolved against Crossref · corpus check 2026-06-10

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