After consuming whey protein following resistance exercise, people eat more slowly, reducing their energy intake by 16.5 kJ per minute on average, regardless of how hungry or full they feel.
Mechanism
Synthesis from 1 study
The protein drink is thick and creamy, so people eat their next meal more slowly. This slower eating lets the stomach fill up before the brain realizes it's full, so they eat less food without feeling hungrier. This happens even though their hunger and fullness feelings don't change.
Most probable mechanism
When a thick, creamy protein drink is consumed, the mouth takes longer to process it, which slows down how fast a person eats their next meal. This slower eating gives the stomach more time to fill up before the brain receives signals to stop eating, so the person eats less food without feeling any hungrier or fuller than usual.
Whey protein isolate forms a viscous, creamy solution in the mouth due to its molecular structure and formulation
Increased oral viscosity prolongs orosensory exposure and extends the duration of mechanical and tactile stimulation during swallowing
Prolonged oral processing reduces the rate of food ingestion, extending meal duration and delaying gastric distension
Slower nutrient delivery to the gut allows satiety signals from gastric stretch and nutrient sensing to accumulate before total caloric intake reaches a threshold for cessation
Energy intake decreases because the individual stops eating before consuming the same total calories as during faster eating, despite unchanged hunger and fullness ratings
Less supported by current evidence, but not ruled out
After digestion, amino acids from whey protein stimulate cells in the small intestine to release hormones that signal the brain to reduce appetite, but this pathway does not explain the slower eating rate observed.
Whey protein is broken down into amino acids in the small intestine
Amino acids activate enteroendocrine cells to secrete cholecystokinin and glucagon-like peptide-1
These hormones bind to receptors on vagal nerve endings in the gut wall
Vagal signals are transmitted to the brainstem, where they inhibit feeding centers
Appetite and food intake decrease as a result of central inhibition of hunger drive
Evidence from Studies
Supporting (1)
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Whey protein consumption after resistance exercise reduces energy intake at a post-exercise meal
Contradicting (0)
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