I take it you have been reading leangains? IMO the 10g BCAA is just a recommendation.
I dont bother with it, and train totally fasted. dont worry, martin berkham has talked enough about the impossibility of losing muscle from fasting in the shorterm. those 10g BCAA are not going to make a difference unless you are an elite builder. If you are concerned, sip a tiny bit of whey protein.