BCAAs pre-workout

BCAAs consist of three amino acids, namely leucine, isoleucine and valine.


I use branch chain amino acids (BCAAs) because I train fasted, and for its added benefits. And is a must use in my opinion…


Muscle Protein Synthesis

Amino acids, especially leucine, triggers muscle protein synthesis even in the absence of exercise.

1) But I use BCAAs pre-workout, because exercise increases blood flow significantly, which results in increased amino acid uptake by the muscles, compared to ingesting BCAAs post-workout.

The MPS response therefore is greater.

2) BCAAs also up-regulates mVps34. mVps34 controls both autophagy and amino acid signalling to mTOR which increase MPS. Being in a fasted state down regulates this protein, but BCAAs pre-workout up-regulates it despite the fact of being in a fasted state which will enhance MPS post-workout.

3) Leucine stimulates mTor which supresses AMPK, (study) as AMPK inhibits MPS, but only for 1-2 hours post-workout.



Intermittent fasting and training fasted are both great tools to speed up fat loss, but by training fasted after an extended period without food (let’s say round ’bout 15 hours), your body will start to break down your muscles for amino acids.

1) Ingesting BCAAs before workout will prevent that from happening by preventing the decrease in the net rate of protein degradation when training fasted (study).

2) Leucine increases fatty acid oxidation significantly in muscle cells and decreases fatty acid synthesis (FAS) expression in adipocytes (study).

So leucine increases the utilization and oxidation of fatty acids by the muscles for fuel and decreases the fat storage rate. Meaning you’ll have more energy during your workout.

Leucine supplementation decreases body weight and fat mass by increasing energy expenditure, fatty acid oxidation and locomotor activity (mice study).

Activation of cellular energy metabolism by leucine favors fatty acid oxidation to CO2 and water in adipocyte (study).


How much BCAAs do you need to take?

50mg/kg for strength athletes on a 1.26g/kg protein diet prevents the loss/decrease of leucine in skeletal muscles (study). So it maintains or rather ensures a positive protein balance during periods of training. 1.26g/kg of protein is a bit low in my opinion.

As for a 85kg individual that would be 4.25g of leucine supplemention pre-workout while on a 107g/day protein diet.



BCAAs are essensial for fasted training to speed up muscle gains and fat loss with the added benefits of a bit extra energy. I personally prefer the 3:1:1 ratio.

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