Understanding Amino Acids For Muscle Gain

Lesson 13 Module 2

Essential vs non-essential amino acids:

Protein is made up of 20 amino acids. These amino acids can broadly be defined as 'essential' and 'non-essential'. A non-essential amino acid is one that your body can produce on its own. An essential amino acid is one your body needs to obtain from your diet.

Here's a list of all essential and non-essential amino acids.


  • Histidine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan
  • Isoleucine*
  • Leucine*
  • Valine*

* BCAAs (Branch Chain Amino Acids).


  • Alanine
  • Arginine
  • Asparagine
  • Tyrosine
  • Aspartate
  • Cysteine
  • Glutamate
  • Glutamine
  • Glycine
  • Proline
  • Serine

Complete vs incomplete proteins:

A complete protein is one in which ALL essential amino acids are present. All animal-based protein sources are complete. Therefore, amino acid profiles are less of a concern for meat-eaters. Vegans may need to focus on their protein intake in more detail to avoid a health deficiency. By combining protein sources across the day, vegans can sufficiently achieve all amino acid requirements needed for optimal health.

Plant proteins in relation to human protein and amino acid nutrition. (Young & Pellet, 1994) (PubMed Link)


Amino acids and muscle gain:

Protein is the only macronutrient that contains nitrogen. Therefore, measuring nitrogen levels is one way of assessing protein balance in the body. The aim is for positive protein (or nitrogen) balance in order to protein Muscle Protein Synthesis and avoid Muscle Protein Breakdown.

Typically negative Nitrogen balance occurs in individuals consuming inadequate protein diet and/or are overtraining. Positive nitrogen balance is associated with higher protein intakes and also where an individual is Resistance Training as this acts as a stimuli for nitrogen/protein accrual.

For muscle gain, all essential amino acid are needed to signal the muscle building process. The absence of one essential amino acid would lead to protein oxidation ("burning"). Again, making it important for vegans to consider their protein sources if building muscle is the specific goal.

Indicator Amino Acid Oxidation: Concept and Application (Elango et al 2008) (Full Text)

Leucine is arguably the MOST important amino acid to consider in the muscle building process. Maximal MPS occurs when you hit a specific 'Leucine Threshold'. Therefore, consuming foods high in Leucine post-workout and throughout the day will help maximise adaptations following resistance training.

Most animal-based protein sources are high in Leucine, ie whey protein. Vegans aiming to build muscle, may want to supplement with Leucine when consuming foods/meals with a low Leucine content.

Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signalling responses after resistance exercise. (West et al 2011) (PubMed Link)

  • This study show the impact of larger post-workout protein feedings on amino acid 'spikes'.

Human Muscle Protein Synthesis is Modulated by Extracellular, Not Intramuscular Amino Acid Availability: A Dose-Response Study. (Bohe et al 2003) (Pubmed Link)

  • This study goes into detail on the concept of the Leucine Threshold.