One of my goals with this blog is to have a quality post on pretty much every topic I frequently get asked about. That way I can always have somewhere solid to send people to whenever they DM me questions like “do branched-chain amino acids (BCAAs) and Essential Amino Acids (EAAs) help with muscle growth?”
I love the idea of that because it means I can do each question justice and give a well thought out response to everything, rather than just giving a basic summary.
For this post in particular, I have avoided writing it for so long. Partly for the same reason it took so long to get a post on creatine on this blog. To me, the practical nature of the question has a simple answer, but the overall topic is complex.
While the key takeaway points are easy to understand, actually writing about it in a way I can be proud of is tough. Either way, throughout this post there will be quite a few relevant points that ideally help a few people.
*If you only care about the simplified outcomes – feel free to jump to the summary at the end*
There are 20 total amino acids in the body.
BCAAs make up 3 of these and include leucine, isoleucine and valine.
“Branched-chain” just refers to the chemical structure. People are interested in BCAAs though because those 3 amino acids are often linked with muscle growth.
Leucine in particular has strongly been linked with muscle growth.
BCAAs account for 35% of the essential amino acids found in muscle. They also account for 40% of the total amino acids required by your body.
Out of those 20 amino acids, 9 (including the 3 BCAAs) are considered essential –
These amino acids are considered essential because they can not be created in the body. The other 11 amino acids can be created by the body. Therefore, EAAs must be consumed through food or supplements.
It is technically more complex than that since there are conditionally essential amino acids. But typically these 9 are what is considered essential.
For the sake of this article, I will mostly be focusing on aspects of physical performance and body composition. There are other proposed benefits outside of that, but it becomes an endless list.
The main reason people consume BCAAs and EAAs is because of the belief that it will either help with muscle growth or muscle retention.
There is a fair bit of research, that in isolation, supports this concept. It is a bit more complex than that, but I will touch on some of it below.
In one study, a group that consumed 5.6g of BCAAs after training had a 22% larger increase in muscle protein synthesis (MPS) than those in the placebo group.
Another study involved adding 5g of BCAAs to a 6.25g of whey protein, which resulted in a comparable amount of MPS in comparison to a group that consumed 25g of whey protein. This is interesting because it is a significantly lower amount of total amino acids.
The above study is also interesting because it indicates that one or more of the individual amino acids in BCAAs is a rate-limiting factor for MPS.
Beyond MPS, another study involving BCAAs showed that performance was 20% better in comparison to control when strength tests were repeated for the second time 24-48 hours after an initial session. This is one aspect of where claims about improved recovery come from.
Fatigue During Exercise
In one study measuring self-reported fatigue, those consuming BCAAs reported 15% less fatigue than the control group.
Delayed Onset Muscle Soreness (DOMs)
This provides support to the idea that BCAAs and EAAs could help reduce DOMs, in terms of both length and severity.
What if Total Protein Intake Is High?
The unfortunate aspect of all of this that makes it difficult to interpret for the average person, is that although BCAAs and EAAs are supplements, they are also still just amino acids. And amino acids are the building blocks of protein. They are still present in our food and other supplements.
Arguably having a high enough total protein intake, makes the majority of benefits of BCAAs and EEAs non-existent.
For example, while there is research supporting BCAAs and an increase in MPS, this increase is typically ~50% less than what it is when a whey protein shake that happens to contain a similar amount of BCAAs is used.
This is because whey protein also contains all 9 EAAs in large amounts, in addition to non-essential amino acids.
While non-essential amino acids, are not essential, it does not mean that consuming them through food has no benefit either. Just because the body can produce them, does not mean that the body WILL produce them in the optimal amounts for muscle growth.
For MPS to be optimised, all 9 EAAs should be present in sufficient amounts, alongside a sufficient amount of non-essential amino acids, whether or not they are coming from food or supplements.
If your total protein intake is high enough, it is incredibly likely that you are getting a sufficient amount of BCAAs and EAAs even without specifically supplementing them.
It is also worth being aware that it is far easier and cheaper to increase your protein intake via a supplement like whey protein, than through an amino acids supplement.
Differences Between EAAs and BCAAs
The difference between EAAs and BCAAs has already been touched on.
Something I wanted to mention though is that I have heard people make claims like “BCAAs don’t work, but EAAs do” due to the logic mentioned above about it being beneficial to have all 9 essential amino acids.
And there is a grain of truth in that.
But the logic still falls apart a bit.
Because when total protein intakes are high enough, there is no evidence that supplementing EAAs leads to any additional muscle growth. It has the same issues that BCAAs do, just to a lesser degree.
The Reported Benefits Come from a Grain of Truth
The claim that MPS is stimulated by the BCAAs is true and stems from the increased intracellular anabolic signalling that occurs, leading to MPS.
And there are a LOT of studies that indicate BCAAs and EAAs lead to things like increased muscle growth and reduced DOMs.
The frustrating part though is that these studies are often done under sub-optimal conditions.
For example, say somebody’s ideal protein intake for muscle growth was 150g, giving him 80g protein + 5g BCAAs/EAAs, would likely give them better results.
Another example of this is that protein quality appears to matter a bit more at lower protein intakes. If you kept it at 80g of protein in that example, replacing 5g of that protein with EAAs might still show improved outcomes.
But if you gave that person 175g protein and then added 5g EAAs on top of that, or as part of that, there likely would be no additional improvements in muscle growth.
Why I Typically Do Not Recommend BCAAs or EAAs
My main thought process is that BCAAs and EAAs do not seem to provide relevant additional benefits under circumstances where total protein is high enough.
If somebody happened to have sub-optimal protein intake, there are easier ways to increase it – either through food, or protein powder.
The muscle growth aspect has been addressed above.
The reported reduction of fatigue during training aspect does not seem to translate to improved performance either.
The DOMs aspect is interesting. I actually do lean in favour of BCAAs and EAAs potentially helping to reduce DOMs. When put into context though, it might be less relevant.
These studies identify a ~33% reduction in DOMs. But often they are still using a suboptimal protein intake. How much of that 33% would have been addressed solely by increasing protein intake? I do not have an answer to that question, but I assume a fair amount of that would be relevant.
I am happy to change my opinion on that if I see compelling research.
And more importantly, these reductions in DOMs do not seem to carry over to tangible training outcomes on a consistent basis. Like it does not seem like these reductions in DOMs are allowing people to train more effectively, build more muscle and improve their strength more.
The idea might have merit, but it still is not something I actively utilise with clients at this stage.
When I Might Recommend BCAAs or EAAs
Although I do not actively recommend BCAAs or EAAs, there are times I am not opposed to it.
One example of this is simply people who like the taste of it, have it a maximum of 1x per day, and add it to water because it encourages them to drink more water.
Subjective Feelings During Training
Another option is those who feel like it helps them when they work out. Personally, while I have not had BCAAs in years, I found that if I had it during a 2-hour workout, I felt better on my last couple of sets for the session than if I did not have it.
Call it placebo or whatever, but if somebody has a strong feeling about it, I reckon it makes sense to keep it in.
For athletes on an exclusively plant-based diet, it is hard to get sufficient amounts of leucine in each meal.
There is research indicating that average-sized athletes likely need ~2-3g of leucine per meal to optimise MPS. When you go through and see what that looks like using plant-based meals, it is actually pretty hard.
This is getting really down into the details, but if a plant-based athlete really wanted to ensure they reach that mark, you could argue that consuming BCAAs or EAAs alongside certain meals could be beneficial.
While I do not actually recommend people who are new to the gym go out of their way to supplement BCAAs or EAAs, a gym chain I work with has it in their gym challenges.
Often the challenge participants are people who are not well trained. Some of them are new to the gym.
The challenge involves pretty intense HIIT workouts, often in combination with a relatively large calorie deficit.
These participants are likely to get pretty extreme DOMs in the first few weeks.
So once again, it could actually make a good deal of sense to supplement EAAs in this position, just in case it does noticeably reduce DOMs.
BCAAs and EAAs are very likely to be beneficial for those with sub-optimal protein intakes. But it is also easier to address those sub-optimal protein intakes through other means such as adding more protein-rich foods, or utilising protein powder.
When total protein is sufficient, they do not seem to provide any relevant additional benefits, outside of some specific circumstances.
Because of this I do not recommend them, but at the other end of the spectrum, I am also not actively opposed to them if somebody happened to want to take them for a specific reason.