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Leucine: how much protein per meal for muscle?

Calculate the amount of protein per meal that provides around 2.5 g of leucine, based on your protein source, goal and number of meals.

Short answer

About 2.5 g of leucine per meal is enough to stimulate muscle building in adults, equivalent to 25 to 30 g of animal protein or 35 to 40 g of plant protein. After age 60, you need a little more. Your daily total still matters more than any individual meal.

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What the tool measures

Leucine: a useful signal, not a magic switch

Leucine is an essential amino acid that helps trigger muscle protein synthesis after a meal. Hence the idea of a leucine “threshold” per meal, often placed around 2 to 3 g.

Dose-response trials support this: in young men after a strength training session, muscle protein synthesis plateaued at around 20 g of egg protein, or about 2 g of leucine. Older men needed about 0.4 g of protein per kilo per meal, compared with 0.24 g in younger men.

This reference point helps avoid meals very low in protein. It replaces neither training nor an adequate daily total. The protein calculator provides that total.

Interpreting the result

Interpret without overpromising

  • Protein per day: your total based on your chosen goal.
  • Per meal: this total spread across your meals, without dropping below the amount that provides the target leucine.
  • Protein to reach the threshold: the amount of protein to aim for in a meal to get around 2.5 g of leucine.
  • Status: whether your current distribution is above, near or below this reference point.

Calculation and assumptions

Methodology

  • Protein per day = weight × 1.2 (maintenance), 1.6 (muscle gain) or 2.0 g/kg (cutting).
  • Target leucine: 2.5 g per meal.
  • Leucine share of protein: 8.5% for an animal source, 8% for a mix, 7% for a plant source. A 2018 analysis found 9% in milk, 7% in eggs, and 5 to 13.5% depending on the plant protein.
  • Protein to reach the threshold = target leucine ÷ leucine share.

Sources consulted

Sources

3 references
  1. Moore et al. (2009) : Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men

    In young men after a workout, muscle protein synthesis reaches a plateau at around 20 g of egg protein.

  2. Moore et al. (2015) : Protein ingestion requires greater relative protein intakes in healthy older versus younger men

    A plateau at around 0.40 g/kg per meal in older men, compared with 0.24 g/kg in young men.

  3. Gorissen et al. (2018) : Protein content and amino acid composition of commercially available plant-based protein isolates

    Leucine content ranges from 5.1% (hemp) to 13.5% (corn) for plant proteins, with 9% for milk and 7% for eggs.

Scope of validity

Limitations to know

  • The leucine threshold is a reference point, not an exact value. Studies mostly involve men and muscle protein synthesis measured a few hours after a meal.
  • Leucine contents are averages: they vary by food.
  • If you have kidney disease, discuss protein intake with your doctor.

Frequently asked questions

Before using the result

How much leucine per meal?

Around 2 to 3 g, equivalent to 25 to 30 g of animal protein or 35 to 40 g of plant protein. After age 60, aim a little higher.

Should you take a leucine supplement?

It's not necessary if your meals contain enough protein. Adding leucine alone to a low-protein meal does not replace a proper portion.

Do plant proteins contain enough leucine?

Often slightly less than animal proteins, but the content varies widely. A slightly larger portion or a mix of sources lets you reach the same benchmark.

Is the leucine threshold more important than total protein?

No. Total daily protein and training matter more. The threshold mainly helps you avoid meals that are too low in protein.

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