Effects of acute and chronic protein intake on metabolism, appetite, and ghrelin during weight loss.
OBJECTIVE
This study evaluated the effects of acute and chronic consumption of higher dietary protein on energy expenditure, macronutrient use, appetite, and appetite-regulating hormones during weight loss in women.


METHODS
Thirty-eight women chronically consuming a 750 kcal/d energy-deficit diet with a protein content of 30% (higher protein-chronic diet, HP-CD, n = 21) or 18% (normal protein-chronic diet, NP-CD, n = 17) for 9 weeks were tested. On separate days, metabolic, appetite, and hormonal responses were measured over 4 hours when the women consumed a higher protein-acute meal (HP-AM) (30% of energy as protein) or a normal protein-acute meal (NP-AM) (18% of energy as protein).


RESULTS
With chronic diet groups combined, HP-AM led to lower respiratory exchange ratio (0.829 +/- 0.005 vs. 0.843 +/- 0.008; p < 0.05), lower carbohydrate oxidation (p < 0.05), and higher fat oxidation (p < 0.05) compared with NP-AM. HP-AM also led to reduced self-reported postprandial hunger (p < 0.001) and desire to eat (p < 0.001) and lower postprandial ghrelin (252 +/- 16 vs. 274 +/- 18 ng/mL x 240 minutes, p < 0.05) compared with NP-AM. No differences in postprandial energy expenditure (PPEE) occurred between meals. When combining acute meals, respiratory exchange ratio was lower (p < 0.05) and protein oxidation (p < 0.001) was higher in the HP-CD vs. NP-CD. An acute meal-by-chronic diet interaction was observed with PPEE such that HP-AM led to greater PPEE in the HP-CD vs. NP-CD (28.7 +/- 2.7 vs. 19.9 +/- 2.7 kcal/min for 195 minutes; p < 0.05).


CONCLUSIONS
During weight loss, thermogenesis and protein use appear to be influenced by chronic protein intake, while appetite and ghrelin are more responsive to acute protein intake.
Leidy
Heather J
HJ
Department of Foods and Nutrition, Ingestive Behavior Research Center, Purdue University, 700 West State Street, West Lafayette, IN 47907, USA. hleidy@purdue.edu
Mattes
Richard D
RD
Campbell
Wayne W
WW
D001066:Appetite / Q000502:physiology*; D001833:Body Temperature Regulation / Q000187:drug effects; D004038:Diet, Reducing; D004044:Dietary Proteins / Q000494:pharmacology*; D002149:Energy Intake; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D054439:Ghrelin; D006801:Humans; D009765:Obesity / Q000178:diet therapy*; D050177:Overweight / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects; D036361:Peptide Hormones / Q000097:blood*; D019518:Postprandial Period; D015431:Weight Loss / Q000502:physiology*
D004044:Dietary Proteins; D054439:Ghrelin; D036361:Peptide Hormones