Consuming 2 grams of leucine with a low-protein meal reduces hunger compared to not taking leucine, and increasing the dose up to 2 grams increases this reduction in hunger.
Mechanism
Synthesis from 4 studies
Leucine from food enters the blood, goes into the brain, and turns on sensors in the hunger center that make you feel full. This happens at 2 grams, and more doesn't make you feel any fuller. Another way leucine might work is by triggering immune signals that also reduce hunger, but the brain...
Most probable mechanism
When leucine enters the bloodstream after eating, it crosses into the brain and turns on specific sensors in the hunger center, which tells the brain to stop feeling hungry and feel full instead.
Oral ingestion of leucine increases plasma leucine concentration in a dose-dependent manner
Elevated plasma leucine crosses the blood-brain barrier via the L-type amino acid transporter LAT1
Leucine activates mTOR signaling in hypothalamic neurons of the arcuate nucleus
Hypothalamic mTOR activation suppresses orexigenic neural circuits and enhances satiety signaling to brainstem and cortical regions
Increased satiety signaling reduces subjective appetite perception and increases fullness ratings
Less supported by current evidence, but not ruled out
Leucine triggers the release of certain immune signals in the blood that reach the brain's hunger center and reduce appetite, even though these signals normally cause inflammation.
Leucine stimulates immune cells and adipose tissue to release interleukin-6 and interleukin-1 beta
Elevated interleukin-6 crosses the blood-brain barrier and acts on hypothalamic neurons to suppress appetite perception
Interleukin-6 overrides the orexigenic effect of tumor necrosis factor-alpha by shifting the inflammatory balance toward appetite suppression
This pro-inflammatory state reduces subjective appetite perception and food intake
Evidence from Studies
Supporting (3)
Community contributions welcome
Consuming Lower-Protein Nutrition Bars with Added Leucine Elicits Postprandial Changes in Appetite Sensations in Healthy Women.
The Effects of Reduced Protein‐Nutrition Bars with Enhanced Leucine Content on Ratings of Fullness in Healthy Women
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.