BCAAs are a collection of three amino acids with a side chain that is branched. They are leucine, isoleucine, and valine (usually in a 2:1:1 ratio).
Leucine itself is known to be an “anabolic factor” and signal for muscle protein synthesis, when calories or protein is low, this anabolic signal appears to help prevent muscle loss or even promote muscle gain. Naturally, it would make sense to take BCAAs. But your needs depend more on how much protein you’re eating during the day.
While BCAAs tend to be high in leucine, so are all complete protein sources. So whether you’re chugging down a protein shake or chomping on a steak, you’re taking in BCAAs and a pretty significant dose of leucine.
Here’s where it gets tricky. Most research on BCAAs compares the consumption of the magical three ingredients to low- or no-protein intake at all. In those scenarios, yes, you want to pump those BCAAs to help prevent muscle loss or even spark muscle gains.
If you’re eating your protein, the speed of absorption and the amino acid amounts take on secondary importance because if the total amount of protein you take in is on par with what your body needs to grow, then you’ll have everything your muscles need.
The exception to the rule occurs when you’re dieting or eating fewer calories.
Some research does suggest that taking in more BCAAs might help you preserve your muscle as you drop fat.