90 Day Trial of Leucine

Beginning August 17, 2026, I will add 3 grams of Leucine to each meal for 90 days and evaluate overall growth.

Breakfast oatmeal will get the dosage along with the Orgain product I use. Will also add a scoop of NOW pea protein.

Two additional shakes will be added to my regimen, each with a scoop of NOW pea protein and the Orgain product for taste.

NOW pea protein tastes bad and is hard to mix without a blender.

Biceps will be measured at the start and end of the 90 day test. Will also be adding 21 day bicep challenge to my mix of gym work. All documented in the paper Workout Log.

Leucine triggers muscle protein synthesis and mTOR signaling in skeletal tissue.

The mTOR signaling pathway is like a manager inside your cells that decides if it is time to grow or time to save energy. It listens to your body's environment and controls how cells build or break down materials.

The Two Managers (mTORC1 and mTORC2)

• mTORC1: Focuses on growth. It senses food and energy to build proteins and block cell cleanup.

• mTORC2: Focuses on survival. It controls the cell's shape and keeps the cell alive.

What Turns It On or Off?

• Food and Nutrients: Eating protein (especially amino acids) turns the pathway on.

• Growth Hormones: Signals like insulin tell the cell that it is time to grow and multiply.

• Low Energy: Fasting or exercise drains cell energy, which turns the pathway off to save resources.

What Does It Do?

• When ON: The cell builds muscles, creates fats, and makes new cell parts.

• When OFF: The cell stops growing and starts a cleanup process (autophagy) to burn old waste for fuel.

Picture a protein factory (or construction site) inside a muscle cell.

• mTORC1 is the site foreman. He decides whether the workers (ribosomes) get to start assembling new proteins.

• The workers are ready and the blueprints (mRNA) are there, but the foreman keeps them on standby until he is sure the raw materials have actually arrived.

• Leucine is the special messenger that arrives with a load of amino-acid “bricks.” When leucine shows up in sufficient amounts, it is sensed by cellular “lookouts” (Sestrin2 and related proteins). Those lookouts then tell the foreman: “The bricks are here—start building.”

Once the foreman (mTOR) gets that leucine signal, he:

1. Moves to the right location on the site (lysosomal surface) and gets switched fully on.

2. Removes the brakes on the assembly lines (by phosphorylating 4E-BP1 and activating S6K1).

3. Orders the workers to begin translating the blueprints into actual protein chains.

Without enough leucine, the foreman stays cautious and keeps protein synthesis throttled down, even if other amino acids are present. With leucine present, the green light goes on and the cell ramps up muscle-protein synthesis.

That is why a leucine-rich meal or supplement can act as a strong anabolic trigger: it is the specific signal that tells mTOR “we have the materials—build.”

More on mTOR. The "m" stands for "mechanization" and the "TOR" stands for Target of Rapamycin.

Rapamycin is a natural compound that was first discovered in the soil of Easter Island. (Weird, huh.)

Target of Rapamycin: Scientists discovered the compound first and noticed it stopped cells from growing. When they searched for the specific protein inside the cell that the compound attaches to, they named that target protein mTOR.

So TOR stops cells... unless you apply Leucine... and turn it on. Short version: Leucine turns on Rapamycin.