Last updated:

25 July 2023

Should you take BCAAs before fasted cardio? Muscle building magazines often say yes, but today you’ll see why the fasted cardio BCAA myth is DEAD WRONG.

should you take bcaas before fasted cardio

Reading time:

3 min read

Have you ever been told that you should take BCAAs before fasted cardio because “they’ll stop you from burning muscle”…?

Of course you have!

Because e-v-e-r-y-b-o-d-y has!

For years this was the cookie cutter advice which was printed in muscle building magazines and handed out in supplement stores around the world in a bid to get you to part with your hard earned cash in the name of more muscle.

But here’s the thing…

… this advice was DEAD WRONG.

should you take bcaas before fasted cardio


At this junction it’s only fair that I redirect some of you to my earlier article where I explained why fasted cardio is not better then regular cardio when it comes to fat loss.

You see, I’m a big fan of fasted cardio, and I know many of my readers are too – but many gym-goers literally only do fasted cardio because they’ve been told it burns more fat, and we know that’s not the case. (1, 2, 3)

So if that’s you then I recommend hightailing your butt to that article then coming back here to read this one.

Still here?


So if your goal is to perform fasted cardio, drinking BCAAs would be a bad idea because BCAA supplements contain calories; meaning you are no longer training in a fasted state.

And this is a sneaky little trick, too, because BCAA supplements often display zero calories on their nutrition labels which makes the user think they can sip on them all day long. But how can a supplement which contains 20 grams of leucine, 5 grams of isoleucine and 5 grams of valine have “0 calories”? It can’t, because that’s essentially 30 grams of protein.

In reality this is a supplement industry loophole, which states that a manufacturer cannot list the calorie content of incomplete proteins (like individual BCAAs).

Branched chain amino acids contain 4.6 calories per gram, so 30 grams of BCAAs would be 138 calories. (4)

Who Is Russ Howe PTI?


Russ has been a personal trainer in the UK since 2002, and provided both training advice and full programs on this website since 2011.

His work has been featured in Men’s Fitness magazine, and the content on this website led to him being voted one of the world’s top 50 fat loss coaches by HuffPost.

Russ’ days are spent coaching men and women in the legendary Powerhouse Gym, and creating new content for the 109,246 followers of his popular free weekly e-mail, which you can join below!


  1. Gonzalez J. T., et al. Breakfast and exercise contingently affect postprandial metabolism and energy balance in physically active males. Br J Nutr (2013).
  2. Hackney K. J., et al. Timing protein intake increases energy expenditure 24 h after resistance training. Int J Sport Nutr Exerc Metab (2011).
  3. Paoli A., et al. Exercising fasting or fed to enhance fat loss? Influence of food intake on respiratory ratio and excess postexercise oxygen consumption after a bout of endurance training. Int J Sport Nutr Exerc Metab (2011).
  4. May M. E., et al. Energy content of diets of variable amino acid composition. Am J Clin Nutr (1990).

Response to “Should You Take BCAAs Before Fasted Cardio?”

  1. Rob Delaney avatar
    Rob Delaney

    Russ you absolute bastard. Where were you 20 years ago when I first started buying Bcaa’s???????

    JK, love your work my man. Learned something new here today!

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