The effect of consuming different dietary protein sources at breakfast upon self rated satiety, peptide YY, glucagon like peptide-1, and subsequent food intake in young and older adults.

Interest in plant-based protein in the UK is increasing due to health, environmental, and ethical considerations. Recent studies have explored how different protein sources impact satiety and related gut hormone responses, with evidence suggesting varied responses between animal-based and plant-based proteins. Skewed protein intake patterns, especially at breakfast, present an opportunity for improving dietary protein distribution in populations who may require increased protein intake but often face appetite reductions. This study determined the acute effect of consuming a plant-based, high protein drink containing 30 g of protein (HPDp); an animal-based, high protein breakfast containing 30 g of protein (HPBa); and a low-protein (10 g), high-carbohydrate breakfast (HCLPB) on satiety hormone responses, subjective appetite and subsequent energy intake in older and younger populations when consumed at breakfast. Eighteen heathy adults completed this within-subject, counterbalanced, cross-over study, (12 under 35 years of age and six over 65 years of age). Measurements for appetite were obtained at baseline, 30, 60, 90, 120, 150, 180, 210 and 240 min, and plasma, GLP-1 and PYY at baseline, 30, 60, 90, 120, 180 min post breakfast consumption. No difference in appetitive responses was found between the HPDp and the energy- and protein-matched HPBa, with both eliciting greater GLP-1 and PYY (both p < 0.004) responses compared with a high carbohydrate, low protein meal. Subjective appetite was also suppressed to a greater extent with HPDp compared with HCLPB (p = 0.001). No differences were observed in ad libitum energy intake.