BCAAs, EAAs: does the ratio matter?

BCAAs, EAAs: does the ratio matter?

What about BCAAs?

When we think intra workout supplementation, we often find ourselves thinking BCAA, BCAA, BCAA, but what about essential amino acids (EAAs)? For years we’ve been led to believe by supplement companies that BCAAs are all you need for intra workout supplementation, but research shows that isn’t the case (1). 

For years companies have tried to get us to use BCAA in various manners 1) all day sipping, which turned out to blunt MPS signalling (so counterintuitive), and thus should not be promoted as a flavoured way to drink water, 2) a bolus use intra work (not helpful since it takes all the EAAs for such benefits (read article below), and 3) using it in between meals to signal muscle protein synthesis for those in a caloric deficit as “an anti-catabolic” agent, which once again does not work (see reference 1). Dieter et al. (2016) found that the usage of BCAAs does not lead to an increase of fat free index in those dieting while supplementing BCAAs (1), a finding consistent with lots of BCAA studies (2).  Essentially BCAAs are not the Holy Grail we’ve been led to believe by supplement companies. 

What does Leucine do?

Leucine itself is a tricky beast. Leucine can increase MPS by 30%. Leucine in theory works because it is a rate limiting step in protein synthesis and by supplementing leucine, you get around the rate limiting step (rate limiting step means this is the means to which a process is limited, i.e. without more leucine, MPS rates are limited). This is due to an intracellular anabolic signaling, which is increased when leucine is supplemented. Leucine, however, is not the only important competent for this process as it does require the other essential amino acids to work best. A major limitation in these studies is that in humans, skeletal muscle is a small amount of your total body mass (2). 

What about EAAs?

A 2011 study performed by the US military (meaning these are very fit individuals) studied the effects of EAA supplementation during endurance exercise; they were interested to see the effects of EAA supplementation on postexercise skeletal muscle metabolism. This study examined the effects of 10 g of EAAs in two different groups: a 3.5 g leucine group or a 1.87 g leucine group (3). Subjects performed one hour of slow steady state (endurance) exercise while consuming their BCAA/EAA mixture over the course of two weeks. 

The interesting finding of this study was that muscle protein synthesis (MPS) was greater in the higher leucine group (by as much as 33%more than the 1.87 g leucine group), showing that leucine amount is key to activating MPS. They also found that whole body protein breakdown was lower. So you may be thinking to yourself, well, that’s pretty common sense, leucine activates MPS, what makes this study unique?

1) This study was done by the US Military, so there is no inherent bias from the funding source 

2) This study shows the importance of leucine, and shows that theratio of BCAAs is not important. For years, people have touted the so called “2:1:1” ratio as best (nor is a majority of research built on the so called “2:1:1” ratio touted as much [4]), but this study shows that ratio does not matter (the high leucine group in this study used essentially a 4:1:1 ratio, refer to figure 1); this study shows as long as you get enough EAAs, leucine content is what’s most important, not the ratio. This study also highlights the importance of EAAs during endurance exercise, an area of research that BCAAs alone have been unable to do so far. 

3) The lack of carbohydrates. A large amount of studies investigating the effects of BCAAs confound the research findings by including carbohydrates with their BCAA or EAA mixture. Not all athletes consume carbohydrates during exercise, making the findings of those studies difficult to extrapolate into real world results. We currently live in an industry that is petrified of carbohydrates even though they have lots of ergogenic potential. 

Why are these findings important? Unlike resistance exercise, endurance exercise istrulycatabolic; endurance exercise results in lower rates of MPS and plasma leucine concentration (3). This means when you are performing resistance exercise, not only are you deficient in plasma leucine content in your blood stream, but you are also deficient in stimulating muscle protein synthesis as well. This one-two combination can have a major catabolic effect on your body. The data from the US military study indicates that increasing leucine availability during endurance exercise promotes skeletal muscle protein anabolism and spares endogenous protein, preventing the catabolic effects of endurance exercise. 

What about protein?

According to the U.S. Dairy Council, whey protein offers the highest concentration of BCAAs of any dietary source of protein at about 26 g of BCAAs per 100 g of protein. Whey protein itself has a multitude of benefits and has the amount of BCAAs/ EAAs one would use when using an intraworkout product. This means if you are simply low on money, whey protein is your best chance to make sure you are getting your muscle protein synthesis rate increase (refer to figure 2). It is important to noted that BCAA products provide “free form” amino acids, so they do not count towards your daily protein intake, and that thedocontain calories unlike what you see on most supplement facts for BCAA products. 

As you can notice, whey protein in general has the amount of amino acids required and is found in nature.  

Take over message

So what’s the take home message? Well, if you are going to take additional amino acids in your diet through a supplement, there are only two things you really should look for: 1) Leucine content. Know how much you are consuming. Take at least 2.5 g or more. 2) Take it with additional EAAs (the full 10 grams, which does include leucine), not just BCAAs, because if you are going to be supplementing, you should supplement what is needed...essential amino acids with a high leucine content. Anyone selling an EAA product with a proprietary blend under 10 grams is not doing you any favours. 


  1. Dieter, B. P., Schoenfeld, B. J., & Aragon, A. A. (2016, May 11). The data do not seem to support a benefit to BCAA supplementation during periods of caloric restriction. Journal of the International Society of Sports Nutrition. BioMed Central Ltd.https://doi.org/10.1186/s12970-016-0128-9

  2. Wolfe, R. (2017). Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?. J Int Soc Sports Nutri 14:30.

  3. Pasiakos, S. M., McClung, H. L., McClung, J. P., Margolis, L. M., Andersen,
    N. E., Cloutier, G. J., Pikosky, M. A., et al. (2011). Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. American Journal of Clinical Nutrition, 94(3), 809-818.

  4. Norton LE, Layman DK. (2006). Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise. J Nutr. 136:533S–7S.

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