some will disagree with this but i always take 5g bcaa about 15min before cardio to safeguard against muscle loss . when i did cardio fasted without bcaa i lost alot of muscle .
even though bcaa do release insulin its not the same as when youve eatern carbs because theres no glucose available to be used as fuel . also the slight difference it makes to the smaller amount of fat burned for me outways the risk of losing muscle .