BCAAs and Fat Burning – Should You Consume BCAAs during Cardio?

Let me start by saying that I support the use of supplemental EAAs and BCAAs during a prep to help:

-preserve lean muscle while dieting

-activate protein synthesis (via key muscle building pathways such as mTOR)

-fuel intense training (via energy metabolism)

-improve hormone balance (testosterone: cortisol ratio)

-enhance recovery and reduce post-workout muscle soreness

-improve glucose tolerance and uptake

What it comes down to however is timing and there is a right and wrong time to take BCAAs, depending on your specific goals.

When taken prior to or during fasted cardio, BCAAs can interfere with optimal fat burning and here’s why:

-BCAAs are high in the amino acid Leucine

-Leucine is a well-known stimulator of the anabolic hormone insulin

-When insulin is released, fat burning is blunted (i.e. slows down)

-During a morning fasted cardio session when burning fat is your primary goal on the program, you want insulin levels to be as low as possible – before, during and immediately after the session.

-BCAAs are also a readily available fuel source that can be used during training


-When taken prior to or during morning fasted cardio sessions they body can rely on the BCAAs for fuel, instead of being forced to tap into stored fat

Critics to this position may say you shouldn’t be concerned with something as “insignificant” as this or refer to studies where subjects consuming BCAAs had lower body fat percentages. My response to this is that its my job and in my nature to pay attention to ALL details, as insignificant as the mainstream fitness community may think they are…and when it comes to these studies about BCAAs and body fat percentages – body fat percentages do NOT confirm that BCAAs help with fat loss, it just means that subjects that consume BCAAs on a training program tend to have higher muscle mass and therefore, lower body fat.

My advice is that if you truly want to look your best – leave no stone unturned, pay attention to the details and stop using reverse psychology and writing everything off as insignificant because you enjoy doing them. Yes, you feel better when you drink BCAAs during training! Of course….you’ve got more stuff to fuel your morning fasted cardio session. But what is the purpose of the cardio? For most of us, it’s to tap into the remaining stored fat, not focus on performance or how we ‘feel’ during the cardio.

This whole myth of losing muscle during cardio is also grossly over-exaggerated. We don’t actually ‘lose’ muscle. Muscles atrophy and hypertrophy. While you may look a little flat and smaller during or after cardio, fill back up with a few meals or have a carb up day and tadaaa – your muscle is back!  If you’re truly concerned with maintaining an anabolic environment during your cardio sessions, you would be better off using the supplement HMB. HMB is a metabolite of leucine, but unlike BCAAs do NOT trigger an insulin response.

Best times to consume EAAs/BCAAs:

-Intra, pre or post weight training

-Post meal to enhance protein synthesis, 1-3x day.


Coach Sean




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