Bodybuilder Fouad Abiad sitting on bench with bottle of essential amino acids in front of him


Coach Justin Harris explains the difference between branched-chain amino acids and essential amino acids.

There are 20 amino acids that make up the proteins in our body. There are 11 that the body can make, and nine that it cannot. The goal of amino acid supplementation is ultimately muscle growth, and you need all 20 amino acids present at the site of protein synthesis for that to occur, but nine of those amino acids cannot be made by the body and must come from the diet—making them essential.

So, what is the difference between essential amino acids (EAAs) and branched-chain amino acids (BCAAs)?

They’re two subsets of the same group, actually. BCAAs (isoleucine, leucine, and valine) are actually essential amino acids themselves. They are three of the nine amino acids (histidine, lysine, methionine, phenylalanine, threonine, and tryptophan are the remaining six). They get their name from their chemical structure, which contains a branched chain of carbon atoms on one side of the molecule.

BCAAs are important because they have anabolic effects in humans—increasing the rate of protein synthesis and decreasing the rate of protein degradation. These effects are mediated through changes in the signaling pathways that control protein synthesis, specifically phosphorylation of mTOR and activation of S6 protein kinase. More specifically, it is the amino acid L-leucine that does this (the L- just means that the chirality of the amino acid is left-handed, which is the handedness of amino acids for all life on earth).

So, if BCAAs are the trigger for protein synthesis, and it’s really only the leucine in BCAAs that is responsible for this, what is the benefit of EAAs? 

There is a difference between triggering protein synthesis and the actual synthesis of new muscle proteins. The gas pedal in your car is the trigger for speed, but if there is no fuel in the tank, you can push the pedal to the floor all day—you’re not going anywhere.

The reason EAAs are important is that they are the minimum requirement for synthesis of new muscle proteins in the body. When a need for protein synthesis is created (via weight training, for example), and the action of this synthesis is stimulated (via leucine), we still need all 20 amino acids to be present at the cell where this is occurring for the body to actually build the new tissue.

As we learned above, 11 of these 20 amino acids can be made by the body, but the nine that can’t—the essential amino acids—must not only come from the diet, but must have been ingested recently enough to be present in the blood at that time, as amino acids cannot be stored by the body for later use.

A convenient way to look at the whole process would be to view it like a home construction site. In order to get a home built you need a homeowner to fund the build, a general contractor to organize and direct the build, and the materials to actually build the home. In this model, you could look at the homeowner as the workout routine, creating a reason for the home to be built. The BCAAs would be the general contractor, mediating when and where each part of the home is to be built. And finally, the EAAs would be the raw materials required for the build. All of them play a role, and all of them are needed for the new construction to be completed.

You can find a full spectrum of all nine EAAs in Silo[9]. This vegan-friendly formula also gives you electrolytes and Covico coconut fruit water powder for hydration support.* Silo[9] can be taken before, during, or after your workouts, or any time throughout the day when you want amino acids and hydration support.*


If you're new to the bodybuilding and fitness game or just looking to take your physique to the next level, investing in a good coach can make all the difference in reaching your goals. With decades of experience, both as a competitor and coach, Harris's knowledge is matched by few in this industry. Whether you are a bodybuilding or fitness competitor, athlete, or someone who is just motivated to make a change, he has a program that's perfect for you.

To learn more about his programs, visit or email him at