BCAAS may be beneficial for training with weights while fasted - we're still learning a lot here!
More research is required in this field, however they can pose a big problem ..
BCAAS Can Hinder Muscle Growth
First of all - as I've always said here on FitnFlexed - get enough protein and BCAAS are useless.
We get about 18-26% of BCAAS in our high quality protein diets if we're doing everything right - so there's no need for concern here.
I see guys sipping BCAAS like crazy, on top of all their protein, and this is a problem.
Because it can actually hinder the optimal use of ingested amino acids (1).
As I state in this article from June 2016 - if you're getting enough protein - FORGET additional BCAAS!
A recent review (2) left us with this:
"Thus, as we speculated, consumption of crystalline BCAA resulted in competitive antagonism for uptake from the gut and into the muscle and was actually not as effective as leucine alone in stimulating MPS. Despite the popularity of BCAA supplements we find shockingly little evidence for their efficacy in promoting MPS or lean mass gains and would advise the use of intact proteins as opposed to a purified combination of BCAA that appear to antagonize each other in terms of transport both into circulation and likely in to the muscle.”
In other words, they ain't all that great, buddy!
As I detail in the link above - those who can benefit from BCAAS are those who have a low protein diet, or not enough leucine from ingested daily protein sources.
Regardless of who you see selling BCAAS, just take this article as the truth - save your money, and eat enough protein!
"Stay Fit, Stay Flexed!"
(1) Dieter BP, Schoenfeld BJ, Aragon AA. The data do not seem to support a benefit to BCAA supplementation during periods of caloric restriction. J Int Soc Sports Nutr. 2016 May 11;13:21. doi: 10.1186/s12970-016-0128-9. eCollection 2016.
(2) Morton RW, McGlory C, Phillips SM. Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy. Front Physiol. 2015 Sep 3;6:245. doi: 10.3389/fphys.2015.00245. eCollection 2015.