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“Do BCAAs Work”; do they help build muscle?

When asking the question “do BCAAs work” for building muscle, the dependent questions that arise in my mind are the following inquiries:

  • How many branch-chain amino acids am I already getting from food?
  • Is that enough to cover the additional demands that muscle building places on my body?

That’s logical, right? After all, amino acids are simply building blocks of protein. Therefore, when we chomp down on a plate of steak and eggs or any other high protein dish, we’re likely getting a slew of amino acids, including the branched-chain variety.

But this isn’t the mindset of many newcomers to bodybuilding. What they mistakenly do instead is ask these types of questions as if they exist in a vacuum. They tend not to wonder “do BCAAs work” from a contextually relative standpoint – at least not one that’s appropriate in this case of a product that’s so abundantly present in the most common protein foods. That often happens because the question “do BCAAs work” (and similar inquiries) arise in their minds from seeing ads that make wild claims about these and other bodybuilding supplements.

Amino Acid Leucine (2)

'Leucine Molecule': Can branched-chain anino acids like this one speed muscle growth when taken immediately after workouts?


In addition to this, the question “do BCAAs work” is different from wondering whether a product like, say… ‘tribulus’ works. That’s because ‘tribulus terrestris’ is not a supplementary form of a compound the body needs and already gets from foods in the diet; it’s a completely nonessential addition to some bodybuilder’s consumables with the idea that it can stimulate endogenous testosterone.

BCAAs (branched-chain amino acids), by contrast, are needed and already consumed quite abundantly by anyone eating a regular diet of animal protein. Obviously, this means the question “do BCAAs work” really boils down to the following more specific question:

“Am I getting enough BCAAs from food?”

“Do BCAAs Work”… and what are they anyway?

Branched-Chain Amino Acids (BCAAs) are the three amino acids: Valine, Leucine, and Isoleucine. They represent a third of the nine essential amino acids and account for 35% of essential amino acids in muscle tissue. The term ‘essential amino acids’ simply means they must be obtained regularly from the diet because the body cannot produce them, as it can with the ‘nonessential amino acids.’

The reason these three are referred to as ‘branched-chain’ is due to their molecular structure. They possess a unique makeup of methyl side chains coming off the nucleuses of the amino acid atoms. For whatever that information’s worth, what might be of more interest to bodybuilders and athletes is the fact that these three specific aminos are gobbled up hungrily by recuperating muscle tissue. Studies have suggested that somewhere between 50% and 90% of amino acids absorbed by muscle in the first three hours after a high protein meal are the branched chain aminos.

And it’s evidence like that which the marketers of BCAAs like to tout. They obviously have a vested interest in having you and me make the following association:

If so much of these three aminos are used by muscle – then I probably need extra amounts of them in order to BUILD more muscle.’

Ah… but not so fast. The question ‘do BCAAs work’ is dependent upon whether bodybuilders and athletes get plenty of these three amino acids with the intake of food. It’s only if we don’t that we’re likely to see benefits from using a BCAA supplement. Some foods that are high in BCAAs are as follows.

  • Beef
  • Poultry
  • Eggs
  • Milk
  • Whey Protein
  • Cheese
  • Ice Cream

Thus, before you and I go out and spend our money on tablets and capsules that are labeled as containing high amounts of BCAAs, we’ve got to first wonder if our intake of some or all of the above foods has our bodies already dumping some excess BCAAs. If they are, then our purchase of a BCAA product would be (quite literally) akin to flushing our money into the sewer.

‘Do BCAAs Work?’ Some mixed research

Although some studies have been done on BCAAs, the research trials are scant and have been a bit eclectic in purpose. What’s often cited as evidence that BCAA supplementation is beneficial is an experiment simply showing that they’re needed. What’s lacking is anything solid indicating they’re required by athletes beyond the amounts provided by high protein foods. This makes answering the question ‘do BCAAs work’ for bodybuilding and strength enhancement only somewhat less speculative than without the studies.

Standing Dumbbell Curls (2)A 2010 study published the ‘Journal of Strength and Conditioning Research’ provided evidence that BCAA supplementation can increase testosterone and decrease cortisol in weight training subjects. Eight men were assigned to either a high BCAA supplement or a placebo for three weeks prior to beginning a one-week, high-intensity workout program. The subjects taking the BCAA concoction ended up with higher testosterone, lower cortisol, and lower creatine kinase levels when blood samples were taken after 2 days and 4 days (respectively) of training.

Beyond whether this four-week study was long or large enough to provide conclusive evidence that you and I need supplemental BCAAs, the question of importance of higher post-workout testosterone levels is also relevant. Would the acute rise of this hormone due to BCAA supplementation result in higher average testosterone levels over the long term? If so, would it be a significant enough difference to have any effect on anabolism? Positive answers to questions like these are often only assumed by those who market branched-chain amino acid supplements.

An earlier study demonstrated that ingestion of BCAAs during and after resistance exercise increases the phosphorylation of proteins involved in the regulation of protein synthesis. That double-blind study was done with seven young male subjects back in 2003 and published in the American Journal of Physiology. The men performed two separate workouts consisting of quadriceps resistance training at 80% of 1RM (one-rep max) for four sets of ten repetitions. In randomized order, using double-blind crossover testing, the subjects consumed a BCAA concoction or placebo before and during the training sessions. Blood samples were taken from the men prior to the start of the study. They were also taken immediately before resistance exercise, 10 min into the workout, immediately after the workout, and during recovery at 15, 30, 60, 90 and 120 minutes after the resistance exercise workout.

What were the results of that study in relation to our “do BCAAs work” question?

They certainly “worked” in raising blood plasma concentrations of leucine, isoleucine, and valine. And the workout sessions themselves increased the amount of P7056K phosphorylation of protein for up to two hours after exercise in both the experimental and control groups. But the groups receiving the BCAA concoction had a 3.5-fold additional increase in the amount of P7056K phosphorylation of protein during exercise recovery.

Does this mean overall inter-workout recuperation was increased by taking BCAAs?

That’s what appears to have never been established. And a positive answer to this question is the only thing that would make the use of BCAA supplementation a worthwhile addition to muscle building (in my opinion).

‘Do BCAAs Work’: Opposing Opinions

As far as expert opinion goes concerning the question “do BCAAs work”, it lies at both extremes of the spectrum. There are guys like Charles Poliquin who appears hell-bent on convincing us that they’re beneficial. On the other side, there are people such as ‘Eleanor Noss Whitney’ (author of Understanding Nutrition) who points out that compared to glucose and fatty acids, BCAAs provide very little fuel. She also says that ordinary protein foods supply an abundance of BCAAs anyway and that supplementation is unnecessary.

On those opinions, I’ll point out two observations: I don’t think Mr. Poliquin is trying to convince us that BCAAs are needed as “fuel” and I don’t think Ms. Whitney adequately notes the protein-sparing effect of those other macro-nutrients. Both points could be driven home – that BCAA supplementation might be beneficial as a recuperation enhancer and that getting enough food might provide all the BCAAs anyone could ever need.

In researching this article, I’ve seen some compelling evidence that BCAA supplements might accelerate inter-workout recuperation. I personally haven’t experimented with them as of this writing. It might be worth noting that I have used heavy doses of whey protein, which is high in Leucine, and never noticed benefits from it beyond what I’d get from beef, chicken, fish, or egg protein.

I would love to hear some anecdotal feedback from readers who’ve experimented with heavy BCAA supplementation.  Even if you’ve only used Leucine supplementation, I’d love to get your experiences in the comment section.


1. Embleton, Phil; Thorne, Gerard. ‘Anabolic Primer: An Information-Packed Reference Guide to Ergogenic Aids for Hardcore Bodybuilders’ (MuscleMag International) 1998 (Pgs. 253-256)
2. Sharp, Carwyn; Pearson, David R. Amino Acid Supplements and Recovery from High-Intensity Resistance Training’ (Journal of Strength and Conditioning Research) April 2010 - Volume 24 - Issue 4 – pp 1125-1130
3. Håkan K. R. Karlsson, Per-Anders Nilsson, Johnny Nilsson, Alexander V. Chibalin, Juleen R. Zierath, and Eva Blomstrand ‘Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise’ (American Journal of Physiology Endocrinology and Metabolism) July 1, 2004 vol. 287 no. 1 E1-E7
4. Whitney, Eleanor Noss; Rolfes, Sharon Rady. ‘Understanding Nutrition’ (Ninth Edition) Wadsworth/Thomson Learning 2002 (Pgs. 492-493)


David thomas

Good information about the BCAA. For those who love the vegetarian foods, mushroom, soya bean and chickpea are the rich source of protein.


I would say that one of the best supplements out there that really works is called "Milk". It contains proteins, fats, carbs, amino acids (including BCAAs) and other ingredients in the right ratio for our bodies to use effectively.


Good article, as usual. As BCAA are vital for building muscle, they of course help to build it. Therefore it is worth rephrasing the question to "are BCAA products worth it". I use BCAA/EAA shakes made from powder, as all the little drinks and vials, caps and tablets tend to be even more overpriced. The basic benefit to me is the same as with a regular protein shake: Speed and convenience. It is easy to use and it does not slow you down as much due to digestion and is therefore very quickly available to your body, plus it is free of carbs and fat. So even if you work very irregular hours and are lucky to squeeze in two workouts per week like me, you can go for it right after work with the equivalent of a nice little steak in your system but without having to cook and eat said steak or feeling stuffed while working out. Yes, you could just use a regular whey or soy shake an hour before you hit the iron but pure BCAAs work even faster.

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