In adults around 74 years old, eating a leucine-enriched protein bar after a low-protein breakfast reduces hunger for six hours as much as eating a 32-gram high-protein meal and more than eating a...
Mechanism
Synthesis from 1 study
The leucine in the bar triggers the gut to release signals that tell the brain to stop feeling hungry. This happens quickly and makes older adults feel just as full as if they had eaten a much larger protein meal, without needing to consume more protein.
Most probable mechanism
After eating a leucine-rich bar, leucine enters the bloodstream and signals the gut to release hormones that tell the brain to stop feeling hungry, making a person feel full even without eating a lot of protein.
Free leucine from the protein bar is rapidly absorbed from the small intestine into the bloodstream, achieving plasma concentrations above 500 µM.
Elevated leucine levels activate nutrient-sensing receptors on enteroendocrine cells in the small intestine, triggering the release of satiety hormones including cholecystokinin, glucagon-like peptide-1, and peptide YY.
These satiety hormones bind to receptors on vagal nerve endings in the gut wall, sending electrical signals to the brainstem and hypothalamus.
In the hypothalamus, these signals suppress neurons that drive hunger and activate neurons that promote fullness, reducing subjective hunger and increasing perceived satiety.
Less supported by current evidence, but not ruled out
Leucine activates a cellular growth pathway in muscle that may indirectly signal the brain to reduce hunger through metabolic changes, though this link is not directly proven in this context.
Elevated plasma leucine activates the mTORC1 signaling complex in skeletal muscle cells.
mTORC1 activation increases muscle protein synthesis and alters cellular energy and amino acid flux.
Metabolic changes in muscle may release signaling molecules that communicate with the brain to reduce appetite.
Evidence from Studies
Supporting (1)
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Consumption of High-Leucine-Containing Protein Bar Following Breakfast Impacts Aminoacidemia and Subjective Appetite in Older Persons
Contradicting (0)
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