The benefits of BCAAs

Posted on 24/01/2020 last updated 08/06/2020

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Branch chain amino acids (BCAAs) are one of the most common sports supplements, often used alongside whey protein, creatine and beta alanine. We all know that one gym bro who’s bag rattles like a snake on the banks of the Mississippi, he’ll happily tell you all the supplements he takes and what you too should be taking to get the gains you want. But what are the actual benefits, what do BCAAs do for you? Do you need to be using them and if not why not?

A while ago we wrote this article and we covered BCAAs in there. A few people got a little upset, because if the rattling gym bro says it’s so then it’s obviously so, regardless of what the evidence says. But enough people use BCAAs and swear by them although it is often said that complete protein sources are better than branch-chain amino acid supplements. In an attempt to separate the wheat from the chaff we have delved a little deeper into some of the research for you.

Evidence for BCAAs

A recent paper had a look at power athletes and whether a BCAA supplement was useful for improving athletic performance and muscle recovery (1). They took resistance trained males athletes and measured them doing a countermovement jump (basically a vertical leap) and a seated shotput test. One group took a placebo while the other group took 20g of BCAAs. Both groups saw a decrease in muscle function post training but the BCAA group demonstrated a statistically significant (small but potentially useful) attenuation of decrements. This led to the conclusion that acute ingestion of BCAAs before and after training may reduce fatigue and aid performance.

Another paper we looked at used BCAAs on long distance runners (2). The aim was to test the effect BCAAs have on muscle soreness, inflammation and muscle damage. The study was a double blinded but was a small study with only 12 participants. Perceptions of muscle soreness and sensations of fatigue were lower in the BCAA group compared with placebo.

Another paper from 2006 (3) looked at a small group of canoeists and measured how supplementation with the amino acid leucine (one of the BCAAs) affected exercise performance. A significant increase in upper body power and rowing time were greater after leucine supplementation.

Based on these three small studies there appears to be some evidence that BCAA supplementation around intensive training may help well-trained individuals to train harder. It might simply be that a slight reduction in the rate of perceived exertion makes them feel like they are training harder, but if there are genuine benefits in terms of improved muscular endurance and reduced fatigue that has to be good, right?

But, we’re also left with a lot of questions here and in most studies involving a BCAA supplement it’s usually BCAAs versus nothing. In order to justify BCAA supplementation on grounds of muscle protein synthesis or attenuating breakdown you’d need to show a unique benefit to BCAA that whole protein couldn’t provide. BCAAs versus whole protein would almost certainly show more of a benefit from whole protein where all the amino acids are present over the BCAAs where just three amino acids are present. Then for performance/fatigue you’d need to show they work better than glucose for the same calorie load, so BCAAs versus carbohydrate and, again, it’s highly likely that the carbohydrate would be at-least as effective at attenuating fatigue.

However, BCAAs are safe for use and even if they aren’t having the effect that you think they are, you can be confident that they aren’t doing you any harm either.

BCAA or protein

Complete protein food contains the 3 branched-chain amino acids so should you really be taking BCAAs or just eating a good amount of protein dense foods? Let’s have a look at why BCAAs may be useful and whether they are superior to complete protein.

Fatigue is caused by the loss of ATP during exercise and muscle tissue can oxidise leucine for energy (4). Branch-chain amino acids obviously contain leucine so it does make sense that consumption of a BCAA supplement would help here. If you are training for hypertrophy, to improve power or aiming for muscle maintenance during a calorie deficit these are all assisted by consumption of leucine (4). One way of achieving these benefits is to take either a BCAA or an isolated leucine supplement. But, seeing as a diet that contains adequate leucine rich protein sources will yield the same results (4,5) it might not be necessary to supplement with BCAAs after-all. BCAAs are safe and will work but so will eating chicken, eggs or drinking a whey protein shake. Obviously, you’re not likely to munch on a grilled chicken breast intra workout but you, like most gym goers, probably do have a shaker cup with a couple of scoops of whey protein in your bag ready to go. Also, it looks as though many of the purported benefits of BCAA supplementation are down to the leucine stimulating muscle protein synthesis.

It’s also important to note that much of the research on BCAA supplementation is done on trained and highly trained individuals which could mean that a slight benefit may be seen in experienced exercisers using BCAAs but for most novice to intermediate exercisers there’s usually a LOT of physical adaptations yet to take place before the need for specific supplementation has to be considered.

To BCAA or not to BCAA

Our personal position is that aiming for good levels of protein through the day, possibly every 3-4 hours to stimulate muscle protein synthesis should be enough. Consuming somewhere between 1.6-2 grams of protein per kilogram of bodyweight to promote muscle growth, when in a slight surplus, and between 1.8-2.2 g/kg for muscle maintenance during hypocaloric periods is ideal.

If you are highly trained and your training volume and intensity is high you may want to consider sports supplements like beta alanine, citrulline malate and creatine.

Often, with supplements of this nature there is a psychological element to it as well. If you take a thing and you think it’s doing you some good, then it’s probably doing you some good, the placebo effect is strong. We have shown that there does appear to be evidence that BCAAs can help improve muscle endurance and reduce fatigue during intensive exercise. It may well be that strength athletes who train for 60-90 minutes, high intensity and functional training athletes for example, may benefit from some intra workout BCAAs and possibly endurance athletes too (maybe mix some in with your electrolytes).

But, as we have already said adequate dietary protein is a more important consideration for most active individuals and there are more evidence based supplements worthy of consideration first. Our friends at have this to say on BCAAs (6):

BCAAs are important to ingest on a daily basis, but many protein sources, such as meat and eggs, already provide BCAAs. Supplementation is unnecessary for people with a sufficiently high protein intake

Because examine look at a LOT of research we tend to follow their advice and always compare our research with theirs, they’re way cleverer than we are.

There is one other consideration worth mentioning here and that is using BCAAs to attenuate catabolism during a fast. This is hypothetical but a lot of physique conscious athletes, or those who have work induced time constraints, train in a fasted state, before breakfast. In this case a BCAA drink prior to training will stimulate MPS and potentially prevent the breakdown of muscle and reduce perceived exertion during the session. This is technically then breaking the fast as you are taking in nutrients and calories (around 30-40 kcal) so, if you fast for health reasons associated with apoptosis there’s a chance that a BCAA supplement is in countenance with this. But, if body composition is your main focus BCAAs might be a better choice than coconut oil in your coffee. But then so would a whey protein shake that offers around 60kcals (only 20kcals more) plus ALL the amino acids and seeing as you probably already have a whey protein powder you can save yourself the extra cash from buying a BCAA supplement. The extra calories won’t make much of a difference if you’re fasted you’re likely already oxidising fats, ingesting any energy source will break the fast so just choose whether you’re going to train fasted or not.


If your diet is low in leucine rich protein sources, maybe you’re a vegan for example, then a BCAA or leucine supplement will surely help.

Until there is a conclusive body of research which proves beyond doubt that BCAAs are as effective for exercise performance, body composition or power output as, say creatine or beta alanine then we’ll remain ever so slightly sceptical. Like we say, if you use BCAAs and you feel they help they are certainly safe and may well be helping in some way but they are by no means essential and could be an unnecessary investment.

Besides that, whey protein tastes much better, have you tried our banana whey yet? It’s awesome!


  1. Gee TI, Deniel S. Branched-chain amino acid supplementation attenuates a decrease in power-producing ability following acute strength training. J Sports Med Phys Fitness 2016;56:1511-7
  2. Branched-chain amino acid supplementation attenuates muscle soreness, muscle ... K Matsumoto; T Koba; K Hamada; M Sakurai; T Higuchi; H Miyata Journal of Sports Medicine and Physical Fitness; Dec 2009; 49, 4; ProQuest Science Journals
  3. Effects of dietary leucine supplementation on exercise performance. Crowe MJ, Weatherson JN, Bowden BF.Eur J Appl Physiol. 2006 Aug; 97(6):664-72. Epub 2005 Oct 29.
  4. A primer on branch chain amino acids Starkie Sowers, CN – Faculty, Huntington College of Health Sciences. 2009.
  5. Pasiakos, S.M., Lieberman, H.R. & McLellan, Effects of Protein Supplements on Muscle Damage, Soreness and Recovery of Muscle Function and Physical Performance: A Systematic Review. T.M. Sports Med (2014) 44: 655. doi:10.1007/s40279-013-0137-7
Ben Coomber and Tom Bainbridge
Ben Coomber & Tom Bainbridge

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