BCAAs and Muscle Preservation

If I took some BCAA’s in the morning before 30 minutes very light cardio (before breakfast,) would it help preserve muscle??
I want to be able to ‘kick start’ muscle growth after fasting all night, but I don’t wanna down a shake before the cardio as I’ll burn it off- If I took the BCAA’s around the cardio, could I take the whey when I got back to kick start the growth??

I was just worried that if I took nothing then I’d lose muscle but if I took the BCAA’s there’d be a chance of not risking muscle breakdown, even if I hadn’t eaten anything and just taken the BCAA’s (even though they don’t contain any calories, right?) I’m not looking to lose bodyfat, but I’m looking to keep my calories within a certain limit, and was wondering if the BCAA’s would be a better idea than whey, as they don’t contain any calories (I assume…)