In obese adults, diets high in protein cause the body to burn more calories during digestion than diets high in carbohydrates or fats, with the increase equal to 30–40% of the calories from protein.
Mechanism
Synthesis from 1 study
Eating more protein makes your body burn extra calories because it takes more work to break down and build proteins from amino acids. This extra energy use raises your daily calorie burn. At the same time, protein keeps your muscles from shrinking and makes you feel fuller, which helps you eat less...
Most probable mechanism
When a person eats a lot of protein, the body uses more energy to break down the protein into amino acids, move those amino acids to the liver, and build new proteins from them. This process creates heat and burns more calories than digesting carbs or fats. The extra energy used comes from the work of the liver and muscles to process and store the amino acids, which raises the total number of calories burned each day.
Dietary protein is broken down into amino acids in the gastrointestinal tract and absorbed into the portal circulation
Amino acids are transported to the liver where they undergo deamination and urea synthesis, consuming ATP and generating heat
Amino acids are used for de novo protein synthesis in skeletal muscle and other tissues, requiring additional ATP for translation initiation and ribosomal activity
The combined metabolic costs of protein digestion, hepatic processing, and tissue protein synthesis elevate resting energy expenditure
Less supported by current evidence, but not ruled out
Eating more protein causes the gut to release hormones that signal fullness to the brain and reduce hunger signals, leading to lower food intake.
Dietary protein stimulates enteroendocrine L cells to secrete GLP-1 and I cells to secrete CCK in the small intestine
GLP-1 and CCK bind to receptors on vagal afferent nerves and hypothalamic nuclei, activating satiety pathways
High-protein intake suppresses ghrelin secretion from gastric P/D1 cells, reducing circulating acylated ghrelin levels
Reduced ghrelin and increased GLP-1/CCK signaling decrease appetite and voluntary caloric intake
Eating more protein keeps muscle from breaking down during weight loss by turning on a cellular switch that tells muscles to build more protein, which helps maintain the body's metabolic rate.
Dietary protein delivers essential amino acids, particularly leucine, to skeletal muscle
Leucine activates the mTOR complex 1 in muscle cells
mTOR activation increases translation initiation and ribosomal biogenesis, enhancing muscle protein synthesis and suppressing proteolysis
Preservation of lean body mass maintains resting energy expenditure during energy restriction
Evidence from Studies
Supporting (1)
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Contradicting (0)
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