When people eat high-protein, low-carb ultra-processed foods, their bodies release more hormones that tell them they’re full (PYY and glucagon) and less of the hunger hormone (ghrelin), which may explain why they eat less.
Scientific Claim
In healthy young adults, a short-term (54-hour) high-protein (30% energy), lower-carbohydrate (29% energy) ultra-processed diet increases postprandial secretion of the satiety hormones peptide YY and glucagon while suppressing ghrelin, suggesting a hormonal mechanism for reduced food intake.
Original Statement
“Postprandial ghrelin levels were lower, whereas glucagon and peptide YY levels were higher with HPLC-UPF compared with NPNC-UPF (secondary outcomes).”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
probability
Can suggest probability/likelihood
Assessment Explanation
While the hormone changes are statistically significant, they are secondary outcomes with no direct manipulation of hormone levels. Causation between hormones and intake is inferred, not proven, so probability language is more appropriate.
More Accurate Statement
“In healthy young adults, a short-term (54-hour) high-protein (30% energy), lower-carbohydrate (29% energy) ultra-processed diet is associated with increased postprandial secretion of the satiety hormones peptide YY and glucagon and reduced ghrelin, suggesting a potential hormonal mechanism for reduced food intake.”
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Randomized Controlled TrialLevel 1bWhether artificially elevating PYY and glucagon mimics the reduced intake seen with high-protein diets.
Whether artificially elevating PYY and glucagon mimics the reduced intake seen with high-protein diets.
What This Would Prove
Whether artificially elevating PYY and glucagon mimics the reduced intake seen with high-protein diets.
Ideal Study Design
A double-blind RCT of 40 healthy adults receiving intravenous infusions of PYY and glucagon vs. saline during ad libitum meals of normal-protein UPFs, measuring energy intake and appetite ratings.
Limitation: Does not reflect natural physiological responses to food.
Animal StudyLevel 4Whether blocking PYY or glucagon receptors abolishes the reduced intake effect of high-protein diets.
Whether blocking PYY or glucagon receptors abolishes the reduced intake effect of high-protein diets.
What This Would Prove
Whether blocking PYY or glucagon receptors abolishes the reduced intake effect of high-protein diets.
Ideal Study Design
A study in 30 rats with genetic knockout of PYY or glucagon receptors, fed high-protein vs. normal-protein diets, measuring food intake, hormone levels, and energy balance.
Limitation: Cannot be directly translated to human physiology or behavior.
Cross-Sectional StudyLevel 3Whether individuals with naturally higher PYY/glucagon responses to protein consume less energy in real life.
Whether individuals with naturally higher PYY/glucagon responses to protein consume less energy in real life.
What This Would Prove
Whether individuals with naturally higher PYY/glucagon responses to protein consume less energy in real life.
Ideal Study Design
A cross-sectional study of 200 adults measuring postprandial PYY, glucagon, and ghrelin responses to a standardized high-protein meal and correlating with habitual energy intake over 7 days of food diaries.
Limitation: Cannot establish direction of causality.
Evidence from Studies
Supporting (1)
Short-term effects of high-protein, lower-carbohydrate ultra-processed foods on human energy balance
This study gave people a high-protein, low-carb ultra-processed diet for just over two days and found that their hunger hormones went down and fullness hormones went up — exactly what the claim says.