CORE MAGAZINE SUMMER 2021

Reason #2: Leucine doesn’t work like lighter fluid.
People wrongly assume: The more leucine (from BCAAs, EAAs, or whole
protein) you take, the more protein synthesis you get. And more protein
synthesis means bigger muscles.
Light those muscles up, baby!
Except the mechanism is more like a dimmer switch, Dr. Phillips explains.
Leucine will turn up the protein synthesis switch—but not indefinitely.
It doesn’t continually make the lights brighter and brighter until it’s just you
and the sun hanging at the gym, getting infinitely more swollen.
Here’s how it actually works:
About 0.5 grams of leucine turns on the lights, initiating muscle protein
synthesis. You’ll find that much in an egg—or any other food that contains at
least 5 grams of complete protein.4 You’ll max your wattage somewhere
around 2-3 grams of leucine, though the exact amount will vary based on
your sex, body size, and age.4-6 You’ll find roughly that much in a meal that
contains ~20-30 grams of complete protein, found in:
3-4 ounces of meat
3-5 eggs
1-2 cups of Greek yogurt or cottage cheese Bottom line: Leucine turns up
muscle protein synthesis, but only to a point.
Reason #3: BCAAs don’t go straight from your mouth to
your muscles.
They first have to make their way through your intestines, and into the
bloodstream. (And many don’t.) Amino acids compete with one another to
enter little doorways (called transporters) to get into the bloodstream. And
they can only use the doors specific to their amino acid type. If you flood your
GI tract with single amino acids from a BCAA supplement, the doors reserved
for single amino acids will get backed up. Instead of your bloodstream, they
end up in your toilet.
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