When healthy young adults consume a high-protein meal with 25% of energy from whey protein, their bodies produce more active GLP-1 and insulin after eating than when they consume the same amount of...
Mechanism
Synthesis from 1 study
Whey protein breaks down into amino acids that strongly trigger fullness hormones, but when you eat a lot of it, all proteins release so many amino acids that the body’s hormone system hits its maximum capacity. Even though whey causes a bigger hormone spike, the feeling of fullness and how much...
Most probable mechanism
When a large amount of whey protein is eaten, it breaks down quickly into specific amino acids that flood the gut and pancreas, causing a strong surge in two hormones—GLP-1 and insulin—that signal fullness. But when the dose is high enough, all proteins release so many amino acids that the system becomes saturated, so even though whey causes a bigger hormone spike, the feeling of fullness and how much food is eaten later stay the same as with other proteins.
Whey protein is rapidly digested in the small intestine, releasing high concentrations of branched-chain and essential amino acids including leucine, lysine, tryptophan, isoleucine, and threonine
Elevated concentrations of these amino acids activate calcium-sensing receptors and G-protein-coupled receptors on enteroendocrine L-cells in the distal small intestine
Activated L-cells secrete active GLP-1 into the bloodstream
Elevated amino acids directly depolarize pancreatic β-cells, triggering calcium influx and insulin secretion
At a high protein dose (25% of energy), amino acid concentrations exceed the physiological threshold required to maximally activate L-cells and β-cells, saturating the secretory capacity of both cell types
Supra-threshold amino acid levels eliminate differential hormonal responses between protein sources, resulting in identical GLP-1 and insulin secretion profiles despite differences in amino acid composition
The satiety signaling pathway downstream of GLP-1 and insulin becomes saturated, so further increases in hormone concentration do not enhance hypothalamic appetite suppression or reduce subsequent energy intake
Evidence from Studies
Supporting (1)
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Dose-dependent satiating effect of whey relative to casein or soy.
Contradicting (0)
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