should you take bcaas before fasted cardio


Stop me if you’ve heard this one before:

“Hey bro, you should take BCAAs before fasted cardio because they’ll stop you losing muscle.”

This is the staple advice found in muscle building magazines for years which is followed by gym enthusiasts around the world.

And today I’m going to show you why it’s DEAD WRONG.

should you take bcaas before fasted cardio


If your goal is to perform FASTED CARDIO, then taking BCAAs beforehand sabotages that goal.

BCAAs contain calories, therefore you are no longer training in a fasted state.

Whoa! Hang on a second! Your tub of BCAAs state they contain ZERO CALORIES? How can this be?!

Well, I spoke about it in this post. The reason BCAAs often have zero calories on the label is because current food industry regulations state that you cannot list the calorie content of incomplete proteins. Seeing as BCAAs only contain leucine, isoleucine, and valine, this is classed as an incomplete protein and therefore listed as 0 kcals on the tub.

In reality, BCAAs contain about 4.6 calories per gram. (1)

Therefore, 30 grams of branched chain amino acids equals 120 calories, and your cardio is NOT fasted.

Another piece of bad advice relating to this is when “experts” claim you should buy a BCAA supplement and “sip on them all day long!”. Without making room in your diet for those calories, you absolutely WILL gain weight. And then they’ll try to sell you a fat burner.

(Because the people who do this ALWAYS have a supplement line.)

fasted cardio bcaa myth


So are you missing out on results by taking BCAAs before cardio and sabotaging your “fasted” state?

I don’t believe so.

Fasted cardio has a reputation for being “better for burning fat”, but this reputation is completely fake.

After all, many of the people who swear by fasted cardio’s awesomeness have been taking BCAAs beforehand for years, therefore not even doing fasted cardio.

I’m not saying fasted cardio is useless, of course. You will still burn calories if you train in a fasted state, and you will still drop body fat if you are consistent in your efforts. It’s also something a lot of people simply enjoy starting the day with (like Jennifer Lopez), because you put yourself into a calorie deficit from the get-go. (2)

But this is merely personal preference.

Research shows fasted cardio is not BETTER for fat loss. You will not burn MORE FAT. You will not lose MORE WEIGHT. Lots of people are able to train harder, and therefore create an even bigger calorie burn, when they train in a fed state – especially if they perform high intensity interval training and/or lift weights, (3, 4)

fasted cardio bcaa myth

So hopefully that puts that myth to bed for you.

There you have it. Now you now why you don’t need to take BCAAs before fasted cardio.

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  1. May, M. E., et al. Energy content of diets of variable amino acid composition. Am J Clin Nutr. (1990)
  2. Gonzalez, J. T., et al. Breakfast and exercise contingently affect postprandial metabolism and energy balance in physically active males. Br J Nutr. (2013)
  3. Hackney, K. J., et al. Timing protein intake increases energy expenditure 24 h after resistance training. Int J Sport Nutr Exerc Metab. (2011)
  4. 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)

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