Abstract
Aim: High-protein diets are considered as useful diets for weight loss programs. We collected randomized
controlled trials that evaluated the effect of protein on appetite and gastrointestinal hormones involved in appetite
regulation.
Methods: Trials were included if participants were healthy adults and isocaloric treatments were used in
control and treatment arms. Random-effects model was used to calculate mean difference and 95% confidence
intervals.
Results: In total, 49 publications for acute and 19 articles for long-term effect of protein were included. In
acute interventions, protein decreased hunger (-7 mm visual analogue scale (VAS), P<0.001), desire to eat
(-5 mm, P = 0.045), and prospective food consumption (-5 mm, P = 0.001) and increased fullness (10 mm,
P<0.001) and satiety (4 mm, P<0.001). There was also a decrease in ghrelin (-20 pg/ml, P<0.001) and increase
in cholecystokinin (30 pg/ml, P<0.001) and glucagon-like peptide-1 (GLP-1) (21 ng/ml, P<0.001), but
no change in gastric inhibitory polypeptide and peptide YY was observed. Appetite markers were affected by
protein doses < 35 g but ghrelin, cholecystokinin, and GLP-1 changed significantly after doses ≥ 35 g. Longterm
ingestion of protein did not affect these outcomes, except for GLP-1 which showed a significant decrease.
Conclusion: Results of this meta-analysis showed that acute ingestion of protein suppresses appetite, decreases
ghrelin, and augments cholecystokinin and GLP-1. Results of long-term trials are inconclusive and further trials
are required before a clear and sound conclusion on these trials could be made.
Faça download completo: Effect of short- and long-term protein consumption on appetite and appetiteregulating gastrointestinal hormones, a systematic review and meta-analysis of randomized controlled trials
