title: Responses in gut hormones and hunger to diets with either high protein or a mixture of protein plus free amino acids supplied under weight-loss conditions.
abstract: High-protein diets are an effective means for weight loss (WL), but the mechanisms are unclear. One hypothesis relates to the release of gut hormones by either protein or amino acids (AA). The present study involved overweight and obese male volunteers (n 18, mean BMI 36·8 kg/m2) who consumed a maintenance diet for 7 d followed by fully randomised 10 d treatments with three iso-energetic WL diets, i.e. with either normal protein (NP, 15% of energy) or high protein (HP, 30%) or with a combination of protein and free AA, each 15% of energy (NPAA). Psychometric ratings of appetite were recorded hourly. On day 10, plasma samples were taken at 30 min intervals over two consecutive 5 h periods (covering post-breakfast and post-lunch) and analysed for AA, glucose and hormones (insulin, total glucose-dependent insulinotropic peptide, active ghrelin and total peptide YY (PYY)) plus leucine kinetics (first 5 h only). Composite hunger was 16% lower for the HP diet than for the NP diet (P<0·01) in the 5 h period after both meals. Plasma essential AA concentrations were greatest within 60 min of each meal for the NPAA diet, but remained elevated for 3-5 h after the HP diet. The three WL diets showed no difference for either fasting concentrations or the postprandial net incremental AUC (net AUCi) for insulin, ghrelin or PYY. No strong correlations were observed between composite hunger scores and net AUCi for either AA or gut peptides. Regulation of hunger may involve subtle interactions, and a range of signals may need to be integrated to produce the overall response.
authors: Rowett Institute of Nutrition and Health (RINH), University of Aberdeen,Bucksburn,AberdeenAB21 9SB,UK.
authors: Gerald E
authors: GE
authors: Lobley
authors: Biomathematics and Statistics Scotland (BioSS),Bucksburn,AberdeenAB21 9SB,UK.
authors: Grietje
authors: G
authors: Holtrop
authors: Biomathematics and Statistics Scotland (BioSS),Bucksburn,AberdeenAB21 9SB,UK.
authors: Graham W
authors: GW
authors: Horgan
authors: Rowett Institute of Nutrition and Health (RINH), University of Aberdeen,Bucksburn,AberdeenAB21 9SB,UK.
authors: David M
authors: DM
authors: Bremner
authors: Rowett Institute of Nutrition and Health (RINH), University of Aberdeen,Bucksburn,AberdeenAB21 9SB,UK.
authors: Claire
authors: C
authors: Fyfe
authors: Rowett Institute of Nutrition and Health (RINH), University of Aberdeen,Bucksburn,AberdeenAB21 9SB,UK.
authors: Alexandra M
authors: AM
authors: Johnstone
mesh_terms: D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000737:chemistry*; D001066:Appetite; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D004038:Diet, Reducing; D004044:Dietary Proteins / Q000737:chemistry*; D005749:Gastric Inhibitory Polypeptide / Q000097:blood; D005768:Gastrointestinal Hormones / Q000097:blood; D054439:Ghrelin / Q000097:blood; D006801:Humans; D006815:Hunger; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000378:metabolism; D019894:Peptide YY / Q000097:blood; D019518:Postprandial Period; D011594:Psychometrics; D014364:Tryptophan / Q000737:chemistry; D015431:Weight Loss; D055815:Young Adult
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D004044:Dietary Proteins; D005768:Gastrointestinal Hormones; D054439:Ghrelin; D019894:Peptide YY; D005749:Gastric Inhibitory Polypeptide; D014364:Tryptophan
keywords: Gut hormones