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WHEY PROTEIN AND SATIETY IN 
HUMANS 
 
 
A thesis presented in partial fulfilment of the requirements for the degree of 
 
Doctor of Philosophy  
in 
Nutritional Sciences 
 
at Massey University, Manawatu campus, Palmerston North, New Zealand. 
 
 
Sylvia Mee Siong Chung Chun Lam 
2013 
 
 i 
Abstract 
Protein is the most satiating macronutrient and there is an effect of 
dietary protein source, with dairy whey protein being particularly effective in 
promoting satiety in adult humans. The underlying cause for this remains to be 
elucidated. The objectives were to confirm that whey protein is more satiating 
than maltodextrin carbohydrate in adult humans, to understand the potential 
mediating factors and to investigate which characteristic of whey protein gives 
rise to its satiating effect. Ad libitum food intake at a subsequent test meal after 
administration of a preload, subjective feelings of appetite (using visual 
analogue scales) and plasma concentrations of satiety-related hormones and 
metabolites were determined. Preload diets enriched with whey protein induced 
a greater reduction in subsequent food intake and suppression in rated feelings 
of appetite compared with maltodextrin carbohydrate (p<0.05). The time of 
consumption of the whey protein preload did not influence the satiety response. 
Plasma concentrations of pancreatic polypeptide hormone, total amino acids, 
and the branched-chain amino acids appear to play an important role in 
mediating the satiating effect of whey protein (sustained increases from 15 to 
120 min following preload consumption, p<0.05). To determine the underlying 
characteristic of whey protein causing the satiating effect, the effects on satiety 
of whey protein components (glycomacropeptide, alpha-lactalbumin, or beta-
lactoglobulin) and a free amino acid mixture simulating the amino acid 
composition of the whey protein were compared with that of the intact whey 
protein. The amino acid composition of whey protein per se appears to be 
important in the regulation of food intake and the induction of satiety. The 
individual constituent proteins or whey protein itself did not promote higher 
satiety than that found based on providing the free amino acids. The absorbed 
amino acid profile would appear to play an important role in mediating the 
satiating effect of whey protein.  
 ii 
Acknowledgements 
This PhD was undertaken at the Riddet Institute (formerly Riddet Centre) and 
the Institute of Food, Nutrition and Human Health (IFNHH), at Palmerston 
North, New Zealand.  
 
I extend my sincerest gratitude to my supervision team: Distinguished 
Professor Paul J. Moughan, for welcoming me on his nutrition team and all his 
guidance as my chief supervisor, Dr Sharon J. Henare for taking over the role 
of supervision from Dr. Ajay Awati and for her encouragement and the helpful 
discussions, and Dr Siva Ganesh (AgResearch Grasslands Research Centre) for 
his statistical input and inspiring me to look at my data in a different manner. 
 
I would like to gratefully acknowledge the Massey University Human Ethics 
Committee for approval of my human trials (Protocol no. 06/59, 08/38 and 
11/47). I would like to thank Dr Mark Williams and Mrs Rosalind Timms 
(Massey Medical Centre), Mrs Maria-Tine Biersteker and Mrs Chris Booth 
(IFNHH) for their assistance with my human trials. I am thankful for Ying Jin, 
Christina Streicher, Jacinta Lee, Heleen van Dijke, Chanapha (Nok) 
Sawatdeenaruenat, Natascha Strobinger, Mehak Dhillon, and Sumon Saha for 
their technical support with my human trials. I would also like to thank 
Professor Marlena Kruger (IFNHH) for the use of the Human Nutrition 
Research Unit for my human trials. A special thanks to the men and women 
who volunteered to take part in the studies, I am sincerely grateful. 
 
I am extremely grateful to Dr Barbara Rolls (Pennsylvania State University, 
US) for her advice in the design and conduct of my first study (Chapter 2). I 
also express my deep sense of gratitude to Associate Professor Hugh R. 
Morton (School of Sports and Exercise, Massey University) for his valuable 
advice on statistical analysis and support in the publication of my first journal 
article (Chapter 2, Physiology & Behavior, 2009, 96, 162–8). 
 iii 
 
I am thankful to the Massey University Animal Ethics Committee for approval 
for my rat trial (Protocol no. 12/07). I would like to extend my thanks to 
Associate Professor Craig Johnson (Institute of Veterinary, Animal and 
Biomedical Sciences, Massey University) for his valuable support in receiving 
approval. I am thankful to Dr Carlos Montoya, Dr Jason Hindmarsh and Mr 
Trent Olson for their assistance. 
 
I would like to thank everyone at the Riddet Institute for their support during 
my PhD, in particular Dr Shane Rutherfurd for his scientific advice on amino 
acid determination and input for the manuscript, Dr Derek Haisman and Mr 
Vikas Mittal for their guidance with product formulation, Miss Maggie Zou for 
her valuable assistance in performing the determination of amino acid in 
plasma samples and Dr Prabhu Balan for his kind support in preparing the 
ELISA assays and providing me with his dissertation. I am also thankful to all 
based at the Institute of Food Nutrition and Human Health for their help, 
especially Mrs Fliss Jackson, Miss Leiza Turnbull and Mrs Elizabeth 
Maforimbo for chemical analysis and Mr Garry Radford and Mr Warwick 
Johnson for the use of the food laboratories.  
 
I am extremely thankful to New Zealand Starch Ltd. for providing me with free 
samples of maltodextrins, Fonterra Co-operative Group Ltd. for supplying me 
with free samples of whey protein isolates, Davisco Foods International Inc. 
for providing free samples of glycomacropeptide, alpha-lactalbumin and beta-
lactoglobulin and Evonik Industries AG for the enormous donation of 
individual pure free amino acids.  
 
I am truly thankful to the Riddet Institute for the financial support through a 
PhD Riddet Scholarship award and funding for my PhD research  as part of the 
Centre of Research Excellence projects. I also thank the Riddet Institute and 
New Zealand Nutrition Society for their assistance with conference attendance. 
 
I would not have completed my PhD without the love and blessings from my 
family and friends. I am extremely thankful to my parents Joseph and Elie 
 iv 
Chung Chun Lam for their constant love and support, to my siblings: Cathy, 
Juliana and Bryan for their encouragement and to my parents-in-law Ross and 
Suzanne Lawrence for their motivation and support during this PhD journey.  
My greatest thanks go to my husband, James Lawrence who gave me the 
strength and encouragement to complete this PhD research. I am dedicating my 
PhD dissertation to my son, Wesley Lawrence. Thank You.  
 v 
Table of contents 
Abstract .............................................................................................. i 
Acknowledgements ........................................................................... ii 
Table of contents .............................................................................. v 
List of Tables ................................................................................... xi 
List of Figures ............................................................................... xiv 
List of Abbreviations ..................................................................... xvi 
Preface .............................................................................................. 1 
Chapter 1 .......................................................................................... 1 
Review of literature ...................................................................................... 1 
1.1. Introduction ...................................................................................... 2 
1.2. Satiety................................................................................................. 3 
1.2.1. Terminology ............................................................................... 3 
1.2.2. Measurement of satiety ............................................................... 5 
1.2.2.1. Rating scales ........................................................................... 5 
1.2.2.2. Food intake ............................................................................. 6 
1.2.3. Experimental designs .................................................................. 8 
1.2.4. Satiating capacity of foods.......................................................... 9 
1.3. Protein and satiety .......................................................................... 10 
1.3.1. Effects of protein intake on satiety ........................................... 10 
1.3.2. Mechanisms by which protein intake affects food intake 
and satiety ................................................................................. 23 
1.3.2.1. Energy expenditure ............................................................... 24 
1.3.2.2. Amino acids .......................................................................... 26 
1.3.2.3. Satiety-related hormones ...................................................... 26 
 vi 
1.3.2.3.1. Ghrelin ................................................................................... 27 
1.3.2.3.2. Cholecystokinin ..................................................................... 28 
1.3.2.3.3. Glucagon-like peptide-1 ........................................................ 29 
1.3.2.3.4. Peptide YY ............................................................................ 29 
1.4. Whey protein and satiety ................................................................ 31 
1.4.1. Nutritional profile of whey protein ........................................... 31 
1.4.2. Effect of whey protein intake on satiety .................................... 33 
1.4.2.1. Dose dependent effect ........................................................... 33 
1.4.2.2. Whey protein versus casein ................................................... 34 
1.4.2.3. Whey protein versus other protein sources ........................... 35 
1.4.2.4. Whey protein versus carbohydrate ........................................ 36 
1.4.3. Mechanisms of action of whey protein ..................................... 43 
1.4.3.1. Protein components ............................................................... 44 
1.4.3.2. Glycomacropeptide ............................................................... 44 
1.4.3.3. Amino acids ........................................................................... 47 
1.5. Conclusions and scope of thesis ...................................................... 48 
1.6. Literature cited ................................................................................ 49 
Chapter 2 ......................................................................................... 76 
The influence of whey protein and glycomacropeptide on satiety in 
adult humans ............................................................................................... 76 
2.1. Abstract ............................................................................................ 77 
2.2. Introduction ..................................................................................... 77 
2.3. Subjects and methods...................................................................... 80 
2.3.1. Subjects ..................................................................................... 80 
2.3.2. Design ........................................................................................ 80 
2.3.3. Preload drink and lunch meal .................................................... 83 
2.3.4. Chemical analysis ...................................................................... 87 
2.3.5. Statistical analysis ..................................................................... 88 
2.4. Results .............................................................................................. 89 
2.4.1. Subject characteristics ............................................................... 89 
2.4.2. Satiety ratings (VAS) ................................................................ 89 
 vii 
2.4.3. Drink palatability ...................................................................... 90 
2.4.4. Food and water intake ............................................................... 93 
2.4.5. Correlation analyses.................................................................. 98 
2.5. Discussion ...................................................................................... 101 
2.6. Literature cited ............................................................................. 104 
Chapter 3 ...................................................................................... 109 
Effect of time of consumption of preloads on measures of satiety in 
healthy normal weight women ................................................................. 109 
3.1. Abstract ......................................................................................... 110 
3.2. Introduction .................................................................................. 110 
3.3. Subjects and methods ................................................................... 112 
3.3.1. Subjects ................................................................................... 112 
3.3.2. Preload drinks and test meal ................................................... 113 
3.3.3. Experimental procedure .......................................................... 115 
3.3.4. Measurements ......................................................................... 116 
3.3.5. Statistical analysis ................................................................... 117 
3.4. Results ............................................................................................ 118 
3.4.1. Study subjects ......................................................................... 118 
3.4.2. Sensory ratings of the preload drinks ..................................... 119 
3.4.3. Drinking and eating time ........................................................ 121 
3.4.4. Water intake ............................................................................ 121 
3.4.5. Ad libitum test meal intake ..................................................... 121 
3.4.6. Total energy intake ................................................................. 122 
3.4.7. Reported food intake for the remainder of the day and full 
24h intake ............................................................................... 124 
3.4.8. Subjective ratings of appetite.................................................. 127 
3.4.9. Nausea..................................................................................... 128 
3.5. Discussion ...................................................................................... 132 
3.5.1. Energy intake .......................................................................... 132 
3.5.2. Study design ........................................................................... 135 
3.5.3. Conclusion .............................................................................. 136 
 viii 
3.6. Literature cited .............................................................................. 137 
Chapter 4 ....................................................................................... 142 
Dietary whey protein influences plasma satiety-related hormones 
and plasma amino acids in adult women ................................................ 142 
4.1. Abstract .......................................................................................... 143 
4.2. Introduction ................................................................................... 143 
4.3. Subjects and methods.................................................................... 145 
4.3.1. Subjects ................................................................................... 145 
4.3.2. Test diets ................................................................................. 148 
4.3.3. Experimental procedure .......................................................... 148 
4.3.4. Blood sample collection and analysis ..................................... 149 
4.3.5. Statistical analysis ................................................................... 151 
4.4. Results ............................................................................................ 151 
4.4.1. Glucose and Insulin ................................................................. 151 
4.4.2. Active Ghrelin ......................................................................... 152 
4.4.3. Leptin ...................................................................................... 152 
4.4.4. Gastrointestinal hormones ....................................................... 155 
4.4.5. Correlations between plasma hormones .................................. 156 
4.4.6. Urea and ammonia .................................................................. 160 
4.4.7. Plasma amino acids ................................................................. 160 
4.5. Discussion ....................................................................................... 166 
4.6. Literature cited .............................................................................. 170 
Chapter 5 ....................................................................................... 177 
The underlying cause of the satiating effect of whey protein: effect 
of whey protein and glycomacropeptide isolate on measures of 
satiety in normal-weight adult women .................................................... 177 
5.1. Abstract .......................................................................................... 178 
5.2. Introduction ................................................................................... 178 
5.3. Subjects and methods.................................................................... 180 
5.3.1. Subjects ................................................................................... 180 
 ix 
5.3.2. Preloads and test meal ............................................................ 181 
5.3.3. Experimental procedure .......................................................... 184 
5.3.4. Statistical analysis ................................................................... 185 
5.4. Results ............................................................................................ 187 
5.4.1. Palatability of the preloads and test meal ............................... 187 
5.4.2. Ad libitum food intake at lunch ............................................... 189 
5.4.3. Subjective ratings of appetite and nausea ............................... 191 
5.4.4. Correlation analyses................................................................ 195 
5.5. Discussion ...................................................................................... 195 
5.6. Literature cited ............................................................................. 199 
Chapter 6 ...................................................................................... 203 
Amino acid content of a whey protein isolate: determined using 
multiple hydrolysis times ......................................................................... 203 
6.1. Abstract ......................................................................................... 204 
6.2. Introduction .................................................................................. 204 
6.3. Materials and methods ................................................................. 206 
6.3.1. Sample .................................................................................... 206 
6.3.2. Tryptophan analysis ................................................................ 206 
6.3.3. Sulphur amino acid analysis ................................................... 207 
6.3.4. Analysis of the ‘acid-stable’ amino acids ............................... 207 
6.3.5. Prediction of amino acid concentrations................................. 208 
6.4. Results ............................................................................................ 209 
6.5. Discussion ...................................................................................... 215 
6.6. Literature cited ............................................................................. 216 
Chapter 7 ...................................................................................... 219 
The underlying cause of the satiating effect of whey protein: effect 
of whey protein components and a free amino acid mixture 
simulating whey protein on measures of satiety in adult women ......... 219 
7.1. Abstract ......................................................................................... 220 
 x 
7.2. Introduction ................................................................................... 220 
7.3. Subjects and methods.................................................................... 223 
7.3.1. Subjects ................................................................................... 223 
7.3.2. Test foods ................................................................................ 224 
7.3.3. Experimental procedure .......................................................... 229 
7.3.4. Questionnaires ......................................................................... 230 
7.3.5. Statistical analyses ................................................................... 230 
7.4. Results ............................................................................................ 231 
7.4.1. Palatability of the preload meals ............................................. 232 
7.4.2. Ad libitum test meal intake and total energy intake ................ 234 
7.4.3. Subjective ratings of appetite .................................................. 237 
7.4.4. Correlation anlyses .................................................................. 240 
7.5. Discussion ....................................................................................... 240 
7.6. Literature cited .............................................................................. 244 
Chapter 8 ....................................................................................... 250 
General Discussion and Conclusion ......................................................... 250 
8.1. Conclusions .................................................................................... 259 
8.2. Recommendations for future research ........................................ 260 
8.3. Literature cited .............................................................................. 261 
Appendices .................................................................................... 267 
Appendix 1 .................................................................................... 268 
Whey protein and satiety: implications for diet and behavior .............. 268 
Appendix 2 .................................................................................... 287 
 xi 
List of Tables 
Table 1.1. Effects of dietary protein on food intake and subjective ratings 
of appetite in normal-weight adult humans. .................................. 13 
Table 1.2. Effects of dietary protein source on food intake and subjective 
ratings of appetite in adult humans. ............................................... 37 
Table 2.1. Ingredient (g as-is basis) and nutrient (per 300ml) compositions 
of the preload drinks. ..................................................................... 84 
Table 2.2. Effect of preload drink on food, specific nutrient (weight or 
percentage of total food energy intake) and water intake at 
lunch 30 min after administration of preload (Mean; n = 50). ...... 94 
Table 2.3. Effect of preload drink on food, water and nutrient intakes at 
lunch in men and women (Mean) .................................................. 96 
Table 3.1. Composition of the preload drinks. ............................................... 114 
Table 3.2. Effects of preload drink and time delay on water, test meal and 
total (preload + test meal) energy intakes in women (Mean; n 
= 19). ............................................................................................ 123 
Table 3.3. Effect of preload drink on food energy and nutrient intakes for 
the “remainder of the day” and “over the whole of the day” 
(breakfast + preload + test meal + remainder of the day; 24 
hour) at the time delay of 120 minutes (Mean; n = 19). .............. 125 
Table 3.4. Effect of preload drink on area under the curves (AUCs) for 
subjective ratings of appetite at the time delay of 120 minutes 
(Mean; n = 19). ............................................................................ 131 
Table 3.5. Mean test meal energy intake (kJ) following consumption of 
three different preload drinks and for time delays of 30, 60, 
and 120 minutes in ninety women. .............................................. 134 
 
 
 
 xii 
Table 4.1. Subject characteristics at baseline (Values are means ± sem, n 
= 18). ............................................................................................ 147 
Table 4.2. Net incremental area under the curve (iAUC) for postprandial 
responses following consumption of the “carbohydrate”-
enriched and “protein”-enriched test drinks. ................................ 159 
Table 4.3. Net incremental area under the curve (iAUC) for plasma 
concentrations of individual amino acids following 
consumption of the carbohydrate-enriched and protein-
enriched test drinks1. .................................................................... 164 
Table 5.1. Composition of the four preload drinks. ........................................ 182 
Table 5.2. Water intake, ad libitum test meal food (g) and energy (kJ ME) 
intakes and total (preload + test meal) energy intake after 
consumption of preloads containing carbohydrate, whey 
protein isolate with high glycomacropeptide (WPI-high GMP), 
whey protein isolate with low glycomacropeptide (WPI-low 
GMP) and glycomacropeptide isolate (GMP). ............................. 190 
Table 5.3. Subjective ratings of appetite and nausea expressed as net 
incremental area under the curve (Net iAUC) following 
ingestion of preloads containing carbohydrate, whey protein 
isolate with high glycomacropeptide (WPI-high GMP), whey 
protein isolate with low glycomacropeptide (WPI-low GMP) 
and glycomacropeptide isolate (GMP). ........................................ 194 
Table 6.1. The amino acid composition (g/100g powder on air-dry basis) 
of whey protein isolate estimated using a least-squares 
nonlinear regression model after multiple hydrolysis times (Ao) 
(mean ± sem), compared with the 24-h hydrolysis value (mean 
± sem) and estimated hydrolysis rate (h) (amount of protein-
bound amino acid released per hour) (mean ± sem) and loss 
rate (l) (amount of protein-bound amino acid destroyed per 
hour) for each amino acid (mean ± sem)1. ................................... 213 
Table 7.1. Composition of the four preload meals enriched with whey 
protein isolate (WPI), alpha-lactalbumin (A-LA), beta-
lactoglobulin (B-LG) and a free amino acid mixture simulating 
the amino acid composition of whey protein isolate (AA). ......... 226 
 xiii 
 
Table 7.2. Palatability scores determined on a 10-cm visual analogue scale 
for the four preload meals containing either whey protein 
isolate (WPI), alpha-lactalbumin (A-LA), beta-lactoglobulin 
(B-LG), or a free amino acid mixture (AA)1. .............................. 233 
 
 xiv 
List of Figures 
Figure 1.1. Overview of the satiety cascade (reproduced with permission 
from Halford & Blundell, 2005), including the three levels of 
operations: (A) neurotransmitter and metabolic interactions in 
the brain, (B) physiological and metabolic events, and (C) 
psychological and behavioural events. ............................................. 4 
Figure 1.2. Protein composition of bovine milk (Adapted with permission 
from Walstra et al., 2006). ............................................................. 32 
Figure 1.3. The enzyme chymosin breaks down κ-casein into para-κ-
casein and caseinomacropeptide (CMP). The latter can 
undergo glycosylation to form glycomacropeptide (GMP). .......... 45 
Figure 2.1. Experimental protocol. ................................................................... 82 
Figure 2.2. a)-d). Subjective VAS ratings throughout the study for the 
different preload drinks: carbohydrate, WPI with naturally 
present GMP, WPI with added GMP and WPI with no GMP. ...... 92 
Figure 2.3. Scatter plot and linear regression line (dashed line) for fullness 
VAS scores at 30 minutes (cm) plotted as a function of food 
intake (g) (n = 50). .......................................................................... 99 
Figure 3.1. Scatter plots and Pearson correlation between VAS-rated 
likeability of the carbohydrate (carb, ■) and protein (pro, ▲) 
preload drinks and amount of food consumed at the lunchtime 
test meal (g) in nineteen women. .................................................. 120 
Figure 4.1. Plasma concentrations of (A) glucose, (B) insulin, (C) ghrelin, 
and (D) leptin in eighteen normal-weight women in response 
to ingestion of carbohydrate-enriched (○) and protein-enriched 
(●) beverages. ............................................................................... 154 
 
 
 
 xv 
Figure 4.2. Plasma concentrations of (A) CCK (cholecystokinin), (B) GIP 
(glucose-dependent insulinotropic polypeptide), (C) GLP-1 
(glucagon-like peptide-1), (D) PP (pancreatic polypeptide), 
and (E) PYY (peptide tyrosine-tyrosine) in eighteen normal-
weight women after ingestion of carbohydrate-enriched (○) 
and protein-enriched (●) beverages. ............................................ 158 
Figure 4.3. Plasma concentrations of (A) urea, (B) ammonia, (C) TAA 
(Total amino acid), and (D) BCAA (Branched-chain amino 
acid) in normal-weight women in response to consumption of 
carbohydrate-enriched (○) and protein-enriched (●) beverages. . 163 
Figure 5.1. VAS ratings of overall likeability, pleasantness of taste and 
likeability of texture and overall sweetness for the four preload 
drinks (Values are means ± sem, n = 22). .................................... 188 
Figure 5.2. Mean subjective VAS ratings of hunger, desire to eat, 
prospective consumption, and fullness in response to ingestion 
of preload drinks containing carbohydrate, whey protein 
isolate with high glycomacropeptide (WPI-high GMP), whey 
protein isolate with low glycomacropeptide (WPI-low GMP) 
and glycomacropeptide isolate (GMP). ....................................... 193 
Figure 6.1. Effect of hydrolysis time (x-axis, h) on the concentration of 
amino acids (y-axis, g/100g) for whey protein isolate................. 211 
Figure 7.1. (A) Amount. (B) Energy. ............................................................ 235 
Figure 7.2. VAS-rated subjective feelings of hunger, desire to eat, 
prospective consumption, and fullness before (baseline, B) and 
after consumption of the four preload meals, and 15 and 30 
min following consumption of the ad libitum test meal. Inset: 
Net incremental areas under the curve (Net iAUC) from 0 to 
120 min in response to the four preload meals. ........................... 239 
 
 xvi 
List of Abbreviations 
~ Approximately 
α Alpha 
α-la Alpha-lactalbumin 
β Beta 
β-lg Beta-lactoglobulin 
γ Gamma 
κ Kappa 
5-HT Serotonin 
A-LA  Alpha-lactalbumin 
AA  Amino acid 
ADA American Diabetes Association 
AgRP Agouti-related peptide 
AMPK Adenosine monophospate-activated protein kinase 
ANOVA Analysis of variance 
AOAC Association of Official Chemists 
ARN Arcuate nucleus 
ATP Adenosine triphosphate 
AUC  Area under the curve 
B-LG Beta-lactoglobulin 
BCAA Branched-chain amino acid 
BMI Body mass index 
BSA Bovine serum albumin 
C Carbohydrate 
Carb Carbohydrate 
 xvii 
CART  Cocaine- and amphetamine-regulated transcript  
CCK Cholecystokinin 
CMP Caseinomacropeptide 
CNS  Central nervous system 
CRF Corticotrophin releasing factor 
DIT Diet-induced thermogenesis 
DPP-IV Dipeptidyl-peptidase-IV 
E Energy 
EAA Essential amino acid 
EDTA Ethylenediaminetetraacetic acid 
EFSA European Food Safety Authority 
ELISA Enzyme-linked immunosorbent assay 
F Fat 
FAO Food and Agricultural Organisation 
FFA Free fatty acids 
GE Gross energy 
GIP Glucose-dependent insulinotropic polypeptide 
GLP-1 Glucagon-like peptide-1 
GMP Glycomacropeptide 
HC High-Carbohydrate 
HF High-Fat 
HP High-Protein 
HPLC High-perfomance liquid chromatography 
iAUC incremental area under the curve 
IFNHH  Institute of Food, Nutrition and Human Health 
Ig Immunoglobulin 
J joule 
 xviii 
kcal kilocalorie 
kJ kilojoule 
MC Melanocortin 
ME  Metabolisable energy 
MJ megajoules  
mTOR rapamycin 
NP Normal-Protein 
NPY Neuropeptide Y 
NTS Nucleus tractus solitaries 
NW Normal-weight 
OPA o-phthalaldehyde 
OW Overweight 
P Protein 
PKU Phenylketonuria 
POMC Pro-opiomelanocortin 
PP Pancreatic polypeptide 
Pro Protein 
PYY Peptide tyrosine-tyrosine 
SE Standard error of mean 
sem Standard error of mean 
T/LNAA Tryptophan Large neutral amino acids ratio 
UNU United Nations University 
VAS Visual analogue scales 
WHO World Health Organisation 
WP Whey protein 
WPI Whey protein isolate