Research

Hormonal

Complete meals must contain a sufficient threshold of leucine (approx. 10.9% of protein from whey) to maximally stimulate muscle protein synthesis (MPS) and mTOR signaling; lower-leucine proteins (wheat/soy) fail to trigger this response despite equal total protein intake.

To maximize muscle growth, prioritize high-leucine protein sources like whey, eggs, or meat in your meals. Ensure each meal contains enough protein (typically 25-30g of high-quality protein) to reach the leucine threshold required to trigger muscle protein synthesis. Simply eating enough total protein throughout the day is insufficient if individual meals lack sufficient leucine.

ModerateSupportsMEDIUM confidence
We determined that whey increased plasma leu, mTOR signaling, and MPS more than wheat at all protein intakes... The leu content of the meals predicted mTOR signaling and peak MPS responses and were closely related to changes in plasma leu.
Layne Norton · Illinois Digital Environment for Access to Learning and Scholarship (University of Illinois at Urbana-Champaign) · 2010

Why this rating

Evidence is derived from rat models; human translation is implied but not directly tested in this specific dissertation.

Source

Leucine is a critical factor determining protein quantity and quality of a complete meal to initiate muscle protein synthesis

Layne Norton · Illinois Digital Environment for Access to Learning and Scholarship (University of Illinois at Urbana-Champaign) · 2010

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