BCAA Supplementation: Placebo Juice

Me and my ex in simpler times. How happy we were, and how little gains we made.

Branched-Chain Amino Acids (BCAAs) hold a special place in my heart. AS THE BIGGEST WASTE OF MONEY EVER. This coming from the girl who once bought apple cider vinegar because it uPs uR mEtAbOLiC rAtE. So you know this shit is serious. I have seen a few PT’s posting on Instagram about the benefits of BCAA supplementation, and it occurred to me just how much misinformation there is out there. And, given the amount of money I wasted on them in the past, I hold a personal grudge against these glorified Boleros, as in my case I didn’t need them at all.

In this article, I will break down what exactly BCAA’s are, what you can use them for and whether you even need to supplement them. Spoiler alert: you probably don’t.

Branched-Chain Amino What Now?

If you are a personal trainer, you may recall from your extensive 2 hour lecture covering the entirety of the macronutrient protein that there are twenty amino acids that make up muscle protein. There are two types of amino acids: essential and non-essential. The body cannot make sufficient amounts of the nine essential amino acids (EAA) itself, therefore adequate intake through the diet is imperative[1]. Conversely, the body can sufficiently produce the eleven non-essential amino acids itself.

The Branched-Chain Amino Acids

In addition to sounding like a terrible band name, the branched-chain amino acids are three of the nine essential amino acids. They are as follows:

#1: Leucine

#2: Isoleucine

#3: Valine

The Role of BCAAs in the Body

BCAAs differ from the other EAAs in that they are not catabolized directly by the liver, as it lacks the enzymes. Instead, they are primarily oxidised in skeletal muscle and other peripheral tissues[2]. The role of BCAAs in the body are multiple and varied, and I have no intention of trying to cover them all in this article. BCAAs have been proven to have significant involvement in multiple physiological processes in the body, and are influential in pathological processes such as insulin resistance, obesity, cardiovascular disease and some genetic disorders[3].

Within skeletal muscle, BCAAs, particularly leucine, are attributed with stimulating protein synthesis after exercise[4]. Leucine has been attributed with further assisting protein synthesis through involvement in the rapamycin (mTOR) signalling pathway[5]. Sounds nice and complicated (and it is), but in essence the mTOR pathway helps stimulate protein synthesis. BCAAs (and other amino acids) may also by used as fuel by skeletal muscle, following liver glycogen depletion.  Therefore, the level of BCAAs in the body decreases following exercise.

Obviously, for BCAAs to fulfil their role in the body, they must be available in sufficient amounts (just like all the essential amino acids). For muscle protein synthesis to occur, all essential amino acids must be present, not just BCAAs (don’t be fooled like me and end up a sucker for marketing). Leucine can send the “u up?” text, but if the other essential aminos aren’t present it’s a fruitless mission.

Key points:

  • BCAAs are essential for muscle protein synthesis, particularly leucine. But so are all EAAs.
  • BCAAs can be used as fuel by the muscles.
  • As BCAA levels decrease after exercise, it makes sense to replenish them following training, to encourage muscle protein synthesis.

This is only a very short synopsis of the role of the BCAAs. I’m not going to get to into the details of each function (to be honest a lot of it is over my head, and I’ll have a better idea once I start my MSc!), as I don’t think it is necessary for the scope of this article. Regardless, you can appreciate that BCAAs are essential for human function.

But is it necessary to supplement your diet with them?

The Role of BCAAs in Sports Nutrition

BCAAs for Endurance Athletes

For the endurance athlete, it was purported that supplementing with BCAAs would improve performance. As stated above, the body can use BCAAs as fuel during times when liver glycogen is low. Therefore, it was hypothesised that supplementing with BCAAs may increase the time taken to fatigue (if you have more glycogen [fuel for skeletal muscles] you can keep going for longer, right?). This was examined in a study of rats exposed to prolonged “endurance” style-exercise[6]. BCAA supplementation was found to increase performance and delay the time to fatigue. However, this was dose-dependent, as excessive supplementation at a higher level actually decreased performance! One study found supplementary BCAA intake to reduce muscle glycogen depletion –a “glycogen-sparing effect”- and prevent deterioration of physical performance[7]. However, it is estimated that this effect is minimal in the trained individual. Therefore, for beginners, supplementation may be beneficial[8].

It is also hypothesised that BCAA supplementation may reduce muscular damage following prolonged exercise. This will be discussed in the next section.

BCAAs in Resistance Training

Muscular hypertrophy (growth) occurs when the muscle is placed under mechanical tension, metabolic stress or damaged. Resistance training provides the stimulus required for this response to occur. It was supposed that BCAA supplementation lead to increased rates of protein synthesis, and therefore aided muscle building. After resistance training, supplemental intake of BCAAs or protein hydrolysate were reported to increase protein synthesis and negate the rate of protein breakdown[9]. That does not mean we can directly infer that BCAAs alone induce muscular hypertrophy and instant #gainz. Two separate systematic reviews of literature found that current studies do not provide enough support for the claim that it drastically stimulates hypertrophy over time[1],[10].

There appears to be support for the claim that it may help preserve muscle mass in hypocaloric states. In trained male individuals (read: not newbz) undertaking a resistance training programme whilst in a calorie deficit, BCAA supplementation aided retention of muscle mass and strength. So, while these participants were losing fat, they were preserving their muscle tissue[9]. This suggests that trained male individuals (bodybuilding/powerlifting competitors etc.) may benefit from BCAA supplementation to aid muscle preservation while “cutting”. I couldn’t find any studies on any other demographics (if you do send them on so I can update this).

It has also been claimed that BCAA supplementation can be advantageous in reducing delayed onset muscle soreness (DOMs). However, systematic review of studies examining this is generally inconclusive, some studies finding it slightly beneficial, others that it is more than likely placebo[10].

There’s Rats Everywhere Nidge: Using Animal Studies to get Human Results (An Aside)

Herein we see the limitations of inferring conclusions based on animal studies. Many of these studies were carried out on rats[1],[6] and not human gym rats. Rodents have a much lower skeletal muscle mass, and their protein synthesis mechanism differs from humans. Therefore, whilst we can draw some hypotheses, without direct human testing it is hard to ascertain the value of these studies for humans.

The Case for Supplementation

We have discussed at length thus far how the body needs BCAAs, but consuming BCAAs in isolation may be of limited benefit to the average trainee.

As with all supplements, they are supplemental (what a stunning conclusion to draw Michelle, fair play). If you can’t get sufficient intake through your diet alone, therein lies the case for supplementation (this goes for all supplements).

Sources of BCAAs

So you need BCAAs. But how do you get them if you don’t want to shell out for a supplement? Contrary to the marketing of supplement companies, it’s actually very easy and found in almost every supermarket. Any complete protein source will contain all the EAAs, and by default BCAAs to varying degrees. Good sources include: pea protein, whey protein, meat, dairy, wheat germ and soya[11], but any Google search will throw out a few good ideas depending on your diet. A post-workout scoop of protein has you covered. Not only that, but its much cheaper, and we all know I love a bargain.

You can imagine that if you are eating a balanced diet with adequate protein intake (0.8-1g/lb bodyweight approximately), you probably have sufficient intake of BCAAs in your diet alone.

Why I’m Mad Today: Claims by Big Pharma

The claims advertised on popular BCAA supplements include:

Supports muscle growth > So will any complete protein source
Support recovery > So will any complete protein source 
Replenish electrolytes > Not the best reason to be supplementing with BCAAs, there are cheaper alternatives (heyi Dioralyte). Also, who tf is drinking BCAAs for electrolyte replenishment? I JUST WANNA TALK.

However, if you struggle to include complete protein sources (can be an issue for some vegans/vegetarians) or are cutting for a show and want to ensure you get every shred of muscle preserved you can (even if the literature shows it’s minimally effective unless you fit the demographics of one specific study), BCAAs may be for you. But get yourself a bag of protein, and save your self the hassle and a few quid in the process.

As an addendum, there is grounds for supplementing with leucine alone[10], but that will be covered in a separate article. If you decide you want to supplement with BCAAs (I will be sad), I actually really liked the flavour of Scivation Xtend BCAAs, particularly the Strawberry & Kiwi, or Watermelon.


In conclusion, I’m sure you can now appreciate from reading this article that a lot of the marketing done around BCAA supplements is hyperbolic and misleading. You can most likely get sufficient intake from your diet alone, assuming it is balanced and meet the criteria discussed. Of course, there are always exceptions, and some may benefit from supplementation. I just find it hard to justify spending money on a supplement that doesn’t really do anything and is expensive for what it is (just like the trainers that recommend BCAAs).

As always, make the decision based on your individual needs and not what some pretty Instagram post tells you.


  1. Wolfe, R.R. (2017) ‘Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?’, Journal of the International Society of Sports Nutrition. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568273/.
  2. Holeček, M. (2018) ‘Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements’, Nutrition & Metabolism. Available at: https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-018-0271-1#:~:text=The%20main%20cause%20of%20the,BCAA%20catabolism%20is%20skeletal%20muscle.
  3. Biswas, D., Duffley, L., Pulinilkunnil, T. (2019) ‘Role of branched-chain amino acid-catabolizing enzyme in intertissue signaling, metabolic remodeling, and energy homeostasis’, FASEB Journal. Available at: https://faseb.onlinelibrary.wiley.com/doi/full/10.1096/fj.201802842RR.
  4. Norton, L.E., Layman, D.K. (2006) ‘Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise’, Journal of Nutrition. Available at: https://pubmed.ncbi.nlm.nih.gov/16424142/.
  5. Blomstrand, E., Eliasson, J., Karlsson, H.K., Köhnke, R. (2006) ‘Branched-Chain Amino Acids Activate Key Enzymes in Protein Synthesis after Physical Exercise’, The Journal of Nutrition. Available at: https://academic.oup.com/jn/article/136/1/269S/4664134.
  6. Falavigna, G., Alves de Araújo, J., Rogero, M.M., de Oliviera Pires, I.S., Pedrosa, R.G., Martins, E., de Castro, I.A., Tirapegui, J. (2012) ‘Effects of diets supplemented with branched-chain amino acids on the performance and fatigue mechanisms of rats submitted to prolonged physical exercise’, Nutrients. Available at: https://pubmed.ncbi.nlm.nih.gov/23201847/.
  7. Kim, D.H., Kim, S.H., Jeong, W.S., Lee, H.L. (2013) ‘Effect of BCAA intake during endurance exercises on fatigue substances, muscle damage substances, and energy metabolism substances’, Journal of Exercise Nutrition & Biochemistry. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4241904/.
  8. Examine.com, Branched-Chain Amino Acids. Available at: https://examine.com/supplements/branched-chain-amino-acids/.
  9. Dudgeon, W.D., Kelley, K.P., Scheet, T.P. (2016) ‘In a single-blind. Matched group design: branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet’, Journal of the International Society of Sports Nutrition. Available at: https://pubmed.ncbi.nlm.nih.gov/26733764/.
  10. Morse, T., Willoughby, D.S. (2019) ‘Efficacy of BCAA supplementation for exercise performance and recovery: a narrative review’, Journal of Nutritional Health & Food Engineering. Available at: https://medcraveonline.com/JNHFE/JNHFE-09-00337.pdf.
  11. Brestensky, M., Patras, P., Nitrayová, S. (2015) ‘Branched chain amino acids and their importance in nutrition’, Journal of Microbiology, Biotechnology and Food Sciences. Available at: https://www.researchgate.net/figure/Content-of-BCAA-in-different-foods-feeds-and-protein-sources-gkg-1-DM_tbl1_282332420.

Published by Michelle Carroll

I am an online coach (MSc Sports & Exercise Nutrition, EQF Level 4 Personal Trainer, PN Level 1) and radiographer (BSc). I believe in empowering others to make better choices for their health through education. I think that the fitness industry has created a disconnect between best practices and “evidence-based” practices. I hope by chronicling my experience as a healthcare professional and my education as a fitness professional I can assist others on the path to bettering themselves.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: