Since I first started in this industry almost 10 years ago there have been several supplements that have been presented as “god-like”. Think about the first time you walked into a supplement store. One of the employees asks about what you are looking for and in most cases. You really have no idea so they continue to ask about your current training goals. Regardless if you are wanting to build muscle or lose body fat there are a small number of supplements that will always be recommended and one of them will be BCAA’s.
In any case, they will tell you that by using BCAA’s you are going to help ‘enhance muscle protein synthesis’. Or ’increase lean muscle mass’. They give you the fancy details on the unique 2:1:1 ratio, 4:1:1 ratio or whatever other ratios that they can sell you on. I have even witnessed said employees from very well-known supplement shops inform the customer who wanted to lose body fat that by using BCAA’s they will actually build muscle while they continue to eat less and fewer calories.
“BCAA’s (Branched-Chain Amino Acids) are essential in supporting muscle recovery and function as they help stimulate protein synthesis resulting in muscle growth.” – a description of BCAA’s from a supplement store/distributor.
In early research, it was thought that by combining these BCAA’s it could aid most gym-goers who want to build muscle and are looking to maximize muscle protein synthesis and minimize muscle protein catabolism. Which would result in net protein synthesis or muscle gain? The consensus in media and gyms across the world has been that BCAA’s, in particular L-Leucine, will get the job done since Leucine is regarded as the most powerful amino at turning on the muscle-building switch.
This has made leucine and BCAAs as a whole a highly popular supplement hypothesized to increase muscle growth.
When it comes to the optimization of muscle protein synthesis, two things are important:
1. Consuming enough protein to provide building blocks (amino acids) to build muscle.
2. Optimizing the signal for muscle protein synthesis by leucine consumption.
Now they may not be completely wrong when it comes to supplementing BCAA’s as a 2017 study concluded; “The present study demonstrated that ingesting of all three BCAAs alone, without concurrent ingestion of other essential amino acids (EAA’s), protein, or macronutrients, stimulated a 22% greater response of muscle myofibrillar protein synthesis following resistance exercise compared with a placebo.” 
Now, this may sound appealing but the researchers went on to then write:
“The magnitude of this increased response of muscle myofibrillar protein synthesis was approximately 50% less than the previously reported muscle myofibrillar protein synthesis response to a dose of Essential Amino Acids containing similar amounts of BCAAs.”
So, EAA’s are at least 50% more effective at building muscle than BCAA’s in isolation!
Now that I have got your attention, let’s run through some of the basics:
Firstly you need to know that Amino Acids are the simplest and fastest absorbed form of protein; much the same way sugar is the simplest and fastest absorbed form of carbohydrates (with some exceptions).
What are BCAAs?
BCAA stands for a branched-chain amino acid. It is said that your body uses 21 amino acids to construct a protein. Within this group of amino acids, you have a very important category of essential amino acids (EAAs) and the non-essential amino acids.
The 9 essential amino acids are what the body cannot synthesize on its own. And must be obtained through your diet. The nonessential amino acids are ones the body can self-generate from a combination of the carbohydrates, fats and essential amino acids, which is why they are dubbed “nonessential.”
BCAAs are a unique “subcategory” of the EAA’s that were given this name “branched-chain” due to their unique branch-like structure. The 3 branched-chain amino acids are:
The nine essential amino acids are:
- Leucine (BCAA)
- Isoleucine (BCAA)
- Valine (BCAA)
The Scoop on EAAS?
Now that you’ve got a basic understanding of the different kinds of amino acids, let’s dive in further to really justify whether or not BCAA’s are “useless.”
“Why essential amino acids are important.”
Our muscles are made of protein, and protein is made up of amino acids. Our bodies synthesize new proteins from these amino acids. It’s important to note that, muscle protein synthesis only occurs if all nine of the essential amino acids are present in sufficient quantities.
This can mean that if just one of the essential amino acids is missing, protein synthesis will come to a stop; thus so will your gains.
For starters, in order for protein synthesis to even begin, the body needs to turn the “on” switch to start the machinery that is assembling these proteins. Something cool about the human body is that there are multiple ways to actually turn this switch “on”.
As discussed above we know that the king amino, Leucine is the most powerful of activators to “turn on” the protein synthesis switch.  The reason being is that Leucine activates the mechanistic target of rapamycin (mTOR) pathway, which is the “switch” that turns on muscle protein synthesis.
Now that you can see the importance of these essential amino acids let’s discuss some of the research highlighting the muscle-building process and BCAA usage:
Please note that in no way am I trying to reinvent the wheel. Nor am I a scientist in the field involved with these types of studies. So a very big thank you is needed to be given to all the leading physique science authorities; in particular for some of the below research references, ‘Menno Henselmann’.
- So BCAAs alone won’t maximize muscle growth. In fact, if you consume BCAAs in isolation, they decrease muscle protein synthesis and turnover or keep you in protein balance.  That’s right. BCAAs don’t normally stimulate muscle protein synthesis (MPS) in isolation. Previous research had inferred the stimulation of MPS from BCAAs by looking at muscle uptake of leucine. However, leucine can be oxidized by the muscle rather than used for protein synthesis.
- Other research had inferred the stimulation of MPS by looking at anabolic signaling. Indeed, leucine activates anabolic signaling. But without other amino acids, particularly the other 6 essential amino acids, to actually build new proteins, this is like turning on a light switch when there’s no power supply.
Basically, even if muscle protein synthesis was increased after BCAA supplementation, without other amino acids, this protein synthesis would have to come from muscle protein breakdown. So you’d, for example, be breaking down your biceps to stimulate growth in your quads.
- In support of BCAA’s ineffectiveness without the other amino acids, Kephart et al. found that BCAA supplementation post-workout is no more effective than sugar at improving recovery after high volume squatting exercise. 
- Spillane et al. confirmed that “when combined with heavy resistance training for 8 weeks, supplementation with 9 g/day of BCAA 30 min before and after exercise had no preferential effects on body composition and muscle performance.” 
- Aguiar et al. again found that supplementing 3 g leucine post-workout for 8 weeks did not increase any measure of strength development or muscle growth (CSA). 
Furthermore, I will also leave you with these final points:
- Whey Protein is more anabolic than BCAA’s since it has a more complete amino acid profile.
- They provide no benefit to muscle mass, strength or muscle soreness.
- There is no evidence of its usefulness when in a caloric restriction.
In conclusion, you may not want to supplement with BCAAs in isolation. As thinking that by sipping them all day you will be aiding in muscle growth simply isn’ t true. A combination of BCAA’s with other amino acids such as EAA’s may be beneficial. As at least in this case you will have the complete spectrum of amino acids available. But if you are already consuming complete protein sources in your day to day dietary intake then there may be no further benefit of supplementing BCAA’s.
 Jackman SR, Witard OC, Philp A, Wallis GA, Baar K and Tipton KD (2017) Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans. Front. Physiol. 8:390
 Drummond MJ, Rasmussen BB. Leucine-Enriched Nutrients and the Regulation of mTOR Signalling and Human Skeletal Muscle Protein Synthesis. Current opinion in clinical nutrition and metabolic care. 2008;11(3):222-226. doi:10.1097/MCO.0b013e3282fa17fb.