The ways protein creates lasting fullness.
What the evidence says
- Greater perceived fullness, elevated satiety hormones after higher-protein meals1
- High-protein meals produce more sustained CCK stimulation and ghrelin suppression than other macronutrient compositions, potentially mediating protein's superior satiating effect2
- Protein-induced satiety may be mainly due to oxidation of amino acids fed in excess, especially with "incomplete" proteins3
- The body has no flexible storage capacity for protein — excess amino acids must be actively oxidized or eliminated, which increases thermogenesis4
- Protein TEF: 20-30% of calories consumed5
- Carbohydrate TEF: 5-10%5
- Fat TEF: 0-3%5
- Protein-induced thermogenesis has important effect on satiety5
- "Complete" proteins (all essential amino acids) produce larger increases in energy expenditure than lower-quality proteins3
- Increased protein turnover accounts for 68% of the acute thermogenic effect of protein feeding4
- Net metabolizable energy of protein is 13 kJ/g (vs 17 kJ/g Atwater factor) due to thermic effect — lower than carbohydrate or fat4
- Large ATP requirement for protein metabolism explains high thermic effect5
- Protein-induced energy expenditure driven by protein and urea synthesis and by gluconeogenesis3
- High-protein meals may increase thermogenesis via up-regulation of uncoupling proteins (UCP-2 in liver, UCP-1 in brown adipose tissue)4
- Hierarchy in macronutrient oxidation: alcohol > protein > carbohydrate > fat5
- Animal (pork) protein produces 2% higher energy expenditure than plant-based (soy) protein4
- Whey protein may increase satiety more than casein: faster gastric emptying and greater stimulation of CCK and GLP-14
- Caseinomacropeptide (15-20% of whey products) stimulates CCK production and increases satiety4