Best Time to Take BCAAs – Pre-Workout? Never?

Best Time to Take BCAAs

BCAAs or branched-chain amino acids, have been one of the most popular workout supplements for over 3 decades but when does science say is the best time to take BCAAs?

There is a lot of “bro science” out there and everyone seems to have an opinion on the matter.

Especially supplement companies wanting to sell you on their products which now often feature BCAAs in both pre-workout and post-workout drinks they insist you need to be taking. In addition to stand alone BCAA powder they often encourage you to drink throughout the day.

But with extensive HUMAN case studies now performed, it’s time to take lose the “bro” and just stick to the science. After all, why would you want to spend hundreds of dollars a year on a product that may not be all that beneficial after all?

In fact, there may be seriously negative consequences to overloading your body with BCAAs instead of whole protein sources.

There are 3 times people suggest you take BCAA’s

  1. Pre-Workout Supplementation
  2. Post-Workout Supplementation
  3. Intermittent Fasting Supplementation

I’m going to dive into the human case studies so you can make an informed decision before shelling out your hard earned cash. But first let’s discuss what exactly are BCAAs and what they do!

What are BCAAs

The human body uses 21 different amino acids to make all of the proteins it needs to function and build muscle.

Out of these 21 amino acids, 9 are considered “essential” which means your body cannot make these 9 so they need to be ingested via food or supplementation.

The 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Most all animal based foods like steak, chicken, eggs, dairy and whey protein drinks contain all 9 essential amino acids in addition to some non-essential ones.

Out the 9 essential, there are are 3 BCAAs or “branched-chain amino acids” which are leucine, isoleucine, and valine.

These 3 amino acids make up about 35% of your body’s muscle protein and early research suggested supplementing with them could potentially enhance protein synthesis. (1)

However, further research has shown that all 9 essential amino acids are needed to enhance protein synthesis. Let’s take a more indepth look at that.

Do BCAAs Increase Protein Synthesis and Build More Muscle?

Human Case Study 1

Researchers gave 24 men after exercise, a 25g supplement of whey protein or 6.5g of whey protein along with either extra leucine or extra essential amino acids without additional leucine.

What they found was 6.5g of whey combined with either the extra leucine or the extra essential amino acids was as effective as 25g of whey protein at stimulating short-term protein synthesis.

HOWEVER, only the 25g of whey supplementation was able to maintain a higher level of protein synthesis for a long period of time.

Their conclusion? Forget trying to focus on specific amino acids and just supplement with a high quality protein like whey as it is more effective. (2)

Multiple Peer Study Review

In 2017, a researcher from the University of Arkansas compiled over 20 different case studies on BCAAs to review.

At the end of his review, he determined that based on all of the research done to date, BCAA supplementation alone showed no ability to increase the rate of protein synthesis because the rate of depletion of the rest of the essential amino acids is too rapid. (3)

This is one of if not the most complete peer reviewed study ever done and if you like nerding out on the science of it all or want to see all the studies looked at, click on the link below for reference #3.

Whey Protein Outperforms Essential Amino Acid Supplementation

Another study compared supplementing with 15g of whey protein with a 6.75g essential amino acid profile vs supplementing with 6.75g of ALL essential amino acids including of course the BCAAs alone.

This study again found whey protein to be far superior in muscle protein accrual than amino acids alone.

This is believed to be, in part, due to a greater insulin response the body has to ingesting a whole protein source. (4)

Whey Protein Outperforms BCAA Supplementation

Despite overwhelming evidence from multiple case studies showing BCAAs do not increase protein synthesis I was able to find one study in which researchers did find a 22% increase with 5.6g of BCAA supplementation following exercise.

However, even if this singular study is correct and the others shown above are wrong there are 2 things which need to be pointed out.

  1. The breakdown of muscle post exercise would still be greater due to not having the supporting amino acids and would counteract much of the increase in protein synthesis. (3)
  2. Supplementing with 20g of whey protein which provides about 4g of BCAAs (less than the 5.6g used in the study) has been shown to increase protein synthesis by 49%. That’s almost double BCAA supplementation. (6)


The research is clear. Stay clear of high priced BCAA supplements if your goal is building muscle and stick to a high quality protein source like Whey.

I would recommend a whey protein isolate with no artificial flavors or sugars added in particular as it’s the most bioavailable form of protein on the market and is low calories as well.

Should I Supplement with BCAAs While Fasting?

This is where things get really interesting as everyone knows you should supplement with BCAAs while in a fasted state right? Not so fast!

Researchers infused 10 fasted men with BCAAs overnight. While the men’s BCAA plasma concentrations increased by 4X and it did help to stim muscle protein breakdown, they saw the following negatives. (7)

  1. Total essential amino acid profile decreased
  2. Muscle protein synthesis severely decreased
  3. Muscle protein turnover was negative


Supplementing with BCAAs in a fasted state may slightly help to stim muscle protein breakdown but it is not going to help you build more muscle.

If your goal is muscle growth, I would suggest starting your nightly fast (in other words the last thing you eat before starting your fast) with a casein protein drink.

Casein is slow digesting protein which also slowly releases its full spectrum of amino acids into your bloodstream.

Supplementing with just 40g of casein protein before bed has been shown to increase protein synthesis by as much as 22% during sleep. (8)

And in another study involving 44 men, researchers saw a significant increase in both strength and muscle size with 27.5g of nightly casein supplementation. (9)

I’m a big believer in intermittent fasting for multiple health reasons so to keep my 16 hours of fasting as strong as possible, my last food consumption is a 30g casein protein drink at 8pm every night so it is as close to bedtime as possible.

I need to point out that some research has shown no significant protein synthesis benefit to a nightly casein protein drink. However if a full spectrum protein is not going to benefit you at night, a BCAA supplement sure won’t.

Do BCAAs Decrease Post Workout Soreness (DOMS)?

Delayed Onset Muscle Soreness or DOMS get us all to some degree after heavy weight workouts and/or long endurance training sessions.

This is the one area BCAAs have been shown to potentially play a big benefit.

Multiple human case studies have shown a significant correlation between pre-workout supplementation and decreases in muscle damage and soreness. (10,11,12,13,13,15)

So supplementing with BCAAs before your workout may be something to consider.

However, as has been demonstrated throughout this article, high quality protein sources are far more superior and beneficial overall.

As of yet, no researchers have compared BCAAs vs whey protein specifically for muscle damage.

While the clinical research has not yet been done, it is logical to expect consuming a whey protein shake before your workout would be as effective if not much more effective than consuming BCAAs based on the overwhelming evidence currently at hand.

Plus whey protein contains lactoferrin, which studies have shown to have an anti-inflammatory effect as well as support a natural immune response to disease. (16)

And if you are concerned that your protein shake needs to be taken after your workout, don’t be.

Multiple studies have now shown it does not matter whether you take your protein shake before or after your workout in terms of strength and muscle gains. (17)


  1. Influence of supplementation with branched-chain amino acids in combination with resistance exercise on p70S6 kinase phosphorylation in resting and exercising human skeletal muscle. Apró W, Blomstrand E. Acta Physiol (Oxf). 2010 Nov;200(3):237-48. – Link
  2. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM. J Physiol. 2012 Jun 1;590(11):2751-65. – Link
  3. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? Wolfe, R.R. Journal of the International Society of Sports Nutrition volume 14, Article number: 30 (2017) – Link
  4. Whey protein ingestion in elderly results in greater muscle protein accrual than ingestion of its constituent essential amino acid content. Christos S. Katsanos, David L. Chinkes, Douglas Paddon-Jones, Xiao-jun Zhang, Asle Aarsland and Robert R. Wolfee. Nutr Res. 2008 Oct; 28(10): 651–658. – Link
  5. Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans. Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KD. Front Physiol. 2017 Jun 7;8:390. – Link
  6. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. Witard OC, Jackman SR, Breen L, Smith K, Selby A, Tipton KD. Am J Clin Nutr. 2014 Jan;99(1):86-95. – Link
  7. Overnight branched-chain amino acid infusion causes sustained suppression of muscle proteolysis. Louard RJ, Barrett EJ, Gelfand RA. Metabolism. 1995 Apr;44(4):424-9. – Link
  8. The Impact of Pre-sleep Protein Ingestion on the Skeletal Muscle Adaptive Response to Exercise in Humans: An Update Tim Snijders, Jorn Trommelen, Imre W. K. Kouw, Andrew M. Holwerda, Lex B. Verdijk and Luc J. C. van Loon. Front. Nutr., 06 March 2019 – Link
  9. Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men. Snijders T, Res PT, Smeets JS, van Vliet S, van Kranenburg J, Maase K, Kies AK, Verdijk LB, van Loon LJ. J Nutr. 2015 Jun;145(6):1178-84. – Link
  10. Branched-chain amino acids augment ammonia metabolism while attenuating protein breakdown during exercise. MacLean DA, Graham TE, Saltin B. Am J Physiol. 1994 Dec;267(6 Pt 1):E1010-22. – Link
  11. Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study. Howatson G, Hoad M, Goodall S, Tallent J, Bell PG, French DN. J Int Soc Sports Nutr. 2012 Jul 12;9:20. – Link
  12. Effects of branched-chain amino acid supplementation on serum creatine kinase and lactate dehydrogenase after prolonged exercise. Coombes JS, McNaughton LR. J Sports Med Phys Fitness. 2000 Sep;40(3):240-6. – Link
  13. Branched-chain amino acid supplementation before squat exercise and delayed-onset muscle soreness. Shimomura Y, Inaguma A, Watanabe S, Yamamoto Y, Muramatsu Y, Bajotto G, Sato J, Shimomura N, Kobayashi H, Mawatari K. Int J Sport Nutr Exerc Metab. 2010 Jun;20(3):236-44. – Link
  14. Effect of BCAA intake during endurance exercises on fatigue substances, muscle damage substances, and energy metabolism substances. Dong-Hee Kim, Seok-Hwan Kim, Woo-Seok Jeong, and Ha-Yan Lee. J Exerc Nutrition Biochem. 2013 Dec; 17(4): 169–180. – Link
  15. Is Branched-Chain Amino Acids Supplementation an Efficient Nutritional Strategy to Alleviate Skeletal Muscle Damage? A Systematic Review. Fouré A, Bendahan D. Nutrients. 2017 Sep 21;9(10). pii: E1047. – Link
  16. Antiinflammatory activities of lactoferrin. Conneely OM. J Am Coll Nutr. 2001 Oct;20(5 Suppl):389S-395S; discussion 396S-397S. – Link
  17. Pre- versus post-exercise protein intake has similar effects on muscular adaptations. Brad Jon Schoenfeld, Alan Aragon, Colin Wilborn, Stacie L. Urbina, Sara E. Hayward, and James Krieger. PeerJ. 2017; 5: e2825. – Link