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Advances in Nutrition logoLink to Advances in Nutrition
. 2013 Jul 8;4(4):418–438. doi: 10.3945/an.113.003723

Effect of Dairy Proteins on Appetite, Energy Expenditure, Body Weight, and Composition: a Review of the Evidence from Controlled Clinical Trials1

Line Q Bendtsen 2,*, Janne K Lorenzen 2, Nathalie T Bendsen 2, Charlotte Rasmussen 3, Arne Astrup 2
PMCID: PMC3941822  PMID: 23858091

Abstract

Evidence supports that a high proportion of calories from protein increases weight loss and prevents weight (re)gain. Proteins are known to induce satiety, increase secretion of gastrointestinal hormones, and increase diet-induced thermogenesis, but less is known about whether various types of proteins exert different metabolic effects. In the Western world, dairy protein, which consists of 80% casein and 20% whey, is a large contributor to our daily protein intake. Casein and whey differ in absorption and digestion rates, with casein being a “slow” protein and whey being a “fast” protein. In addition, they differ in amino acid composition. This review examines whether casein, whey, and other protein sources exert different metabolic effects and targets to clarify the underlying mechanisms. Data indicate that whey is more satiating in the short term, whereas casein is more satiating in the long term. In addition, some studies indicate that whey stimulates the secretion of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide more than other proteins. However, for the satiety (cholecystokinin and peptide YY) and hunger-stimulating (ghrelin) hormones, no clear evidence exists that 1 protein source has a greater stimulating effect compared with others. Likewise, no clear evidence exists that 1 protein source results in higher diet-induced thermogenesis and promotes more beneficial changes in body weight and composition compared with other protein sources. However, data indicate that amino acid composition, rate of absorption, and protein/food texture may be important factors for protein-stimulated metabolic effects.

Introduction

With the increasing prevalence of obesity and metabolic disorders, much effort has been placed in the study of the obesogenic and metabolic effects of specific micro- and macronutrients. Dietary proteins, in particular, have been studied extensively during recent years, and accumulating evidence supports that a high proportion of dietary energy from protein increases weight loss and prevents weight (re)gain (13). The beneficial effect of a high-protein intake seems to be due to increased diet-induced thermogenesis (DIT)4 (4), increased satiety (3, 5) and decreased hunger (2), which is suggested to be mediated through gastrointestinal (GI) hormones. Proteins have unique characteristics related to its source, content of amino acids, and absorption kinetics. It is therefore speculated that proteins from different sources have diverse metabolic effects (6), and some evidence exists that different protein sources differ in their satiating capacity (79). In the Western world, dairy products are a major source of dietary protein, and some studies have shown promising effects of dairy consumption on body weight and composition (10, 11). However, results are conflicting, and evidence from 2 recent meta-analyses (12, 13) indicates that dairy intake combined with energy restriction, but not combined with ad libitum diets, may favor weight loss.

Dairy protein is made up of 2 major classes of proteins: casein (80%) and whey (20%). Bovine casein consists of αs1- (∼37%), αs2- (∼10%), β- (∼35%), and κ-caseins (∼12%). Caseins are phosphoproteins that precipitate from raw milk by acidification. The phosphoproteins are dispersed in milk in the form of micelles that are stabilized by κ-caseins. The casein micelle granules are maintained as a colloidal suspension in milk. In contrast, whey proteins are the proteins that remain soluble after precipitation of casein and consist of ∼50% β-lactoglobulin, 20% α-lactalbumin (αlac), 10% albumin, and lactoferrin with lactoperoxidase making up the rest (1416). Casein and whey are both complete proteins containing all essential amino acids, but they differ in the way in which they are digested and absorbed. The concept of “slow” and “fast” proteins was introduced by Boirie et al. (17) in 1997. Casein, unlike whey, coagulates in the acidic environment in the stomach, which delays its gastric emptying and induces a slow postprandial increase in plasma amino acids. Whey, on the contrary, induces a fast, high, and transient increase in plasma amino acids (17). Some studies have suggested that whey is more satiating than casein (7, 18). Furthermore, it is suggested that whey and casein may affect DIT and body weight to different extents (9, 19).

The aim of this review is to examine the existing evidence from controlled clinical trials investigating the effects of consumption of dairy protein (total dairy protein, whey, and/or casein) and other protein sources on appetite regulation, energy expenditure, body weight, and body composition. Furthermore, the review aims to elucidate the potential mechanisms underlying the protein-specific effects.

Studies eligible for inclusion in this review were identified by searching 6 electronic databases (PubMed, Web of Sciences, MEDLINE, EMBASE, Cab Abstracts, and Cochrane Library) for controlled clinical trials examining the effects of dairy proteins, whey, and/or casein on appetite, GI hormones, energy expenditure, body weight, and body composition in healthy humans. Included studies are presented in Table 1 (appetite), Table 2 (energy expenditure), and Table 3 (body weight and composition).

Table 1.

Controlled clinical trials with appetite ratings, energy intake and/or GI hormone response as outcome1

Intervention
Outcome2
Reference Popopulation Design Diet EI Appetite (VAS) GI hormones
Acheson et al. 2011 (9) 23 lean men and women Randomized, double-blind, crossover (MT)3 Meals (shakes), energy density 1 kcal/g (459 kcal): whey, casein, soy (all 50 E% P) or CHO (isocaloric) 330 min (AUC):
(Switzerland) Desire to eat, hunger, and prospective food consumption: whey > casein (P < 0.005), whey > soy (P < 0.01), casein = soy
Fullness: casein > whey (P < 0.005), soy > whey (P < 0.01), casein = soy
Akhavan et al. 2010 (60) Study I: 2 randomized, crossover studies (MT) 300-mL liquid preloads (∼50 kcal): Ad libitum meal after 30 min (study I): 95 min (study I) and 170 min (study II):
(Canada) 16 men Study I: whey (10, 20, 30, or 40 g) or water 10 g whey = 20 g whey = 30 g whey = 40 g whey Appetite: study I: 10 g whey = 20 g whey = 30 g whey = 40 g whey; study II: 5 g whey = 10 g whey = 20 g whey = 40 g whey; study II: 10 g whey = 10 g WPH
Study II: Study II: whey (5, 10, 20 g), WPH (10 g) or water
22 men and women
Alfenas et al. 2010 (42) 26 normal-weight men and women Randomized, crossover (7 d) Served as breakfast shakes on 7 consecutive days, 0.5 g P/kg BW (∼265 kcal): whey, casein, soy (∼25 g P), or control (∼8.5 g P) 24-h EI: 120 min:
(Brazil) 24 completed the first 3 sessions, only 10 completed the soy session Whey > casein (P = 0.02) Whey = casein = soy
Whey = soy
Casein = soy
Anderson et al. 2004 (38) Study I: 4 crossover studies (3 of which are relevant for the aim of this review) (MT) 400-mL preloads (833 kJ): Ad libitum meal after 60 min:
(Canada) 13 young men
Study II: Study I: whey, soy, egg albumen, sucrose (all 0.65 g/kg BW), or water Study I: whey = soy, whey < egg albumin (P < 0.05)
22 young men Study II: whey, egg albumen (both 50 g P), or water Study II: whey < egg albumin (P < 0.05)
Study III: Study III: intact whey, WPH (both 50 g P), or water Ad libitum meal after 120 min (study III): whey = WPH
10 young men
Baer et al., 2011 (43) 90 overweight and obese men and women Randomized, double-blind, parallel (23 wk) Supplements, 2 packets/d (1670 kJ/d) included in usual diet: whey, soy (both ∼28 g P/packet), or CHO (isocaloric) 24-h dietary records (every 10th day): Before evening meal at wk 23: Ghrelin (0, 12, 16, 20, 23 wk):
(USA) 73 completers Whey = soy Hunger, desire to eat, prospective food consumption and fullness: whey = soy Whey < soy (P = 0.04)
Bowen et al., 2006 (41) 72 normal-weight and obese men Randomized, crossover (MT) Liquid preloads (∼1.1 MJ): Ad libitum meal after 180 min: 180 min: GLP-1, CCK and ghrelin:
(Australia) whey, soy, gluten (all 71 E% P), or glucose (isocaloric) Whey = soy = gluten Whey = soy = gluten Whey = soy = gluten
Bowen et al., 2006 (40) 19 overweight and obese men Randomized, crossover (MT) Liquid preloads (∼1 MJ): whey, casein (both ∼52 g P), lactose, or glucose (both isocaloric) Ad libitum lunch after 180 min: Appetite during 180 min: CCK (AUC 180 min):
(Australia) Whey = casein Whey = casein Whey = casein
Ghrelin (at 180 min):
Whey = casein
Burton-Freeman, 2008 (30) 20 normal-weight men and women Randomized, double-blind, crossover (MT) 300 mL semisolid preloads (∼1 MJ): whey, whey w/o GMP (both 44 E% P), GMP (3 E% P), or CHO (isocaloric) Ad libitum lunch after 75 min: 75 min after preload consumption (prelunch): CCK:
(USA) Whey = whey w/o GMP = control = GMP Women: 75 min after preload consumption (prelunch):
Hunger, desire to eat, and prospective consumption: whey and whey w/o GMP < GMP (P < 0.05) Women:
Fullness: whey and whey w/o GMP > GMP and control (P < 0.05) Whey and whey w/o GMP > GMP (P < 0.05)
Men: Men:
Appetite: Whey w/o GMP > whey (P < 0.05), GMP (P = 0.07)
whey = whey w/o GMP = GMP 105 min post preload consumption (post lunch):
105 min after preload consumption (postlunch): Women:
Women: GMP > whey w/o GMP (P < 0.05)
Fullness and prospective consumption: whey = whey w/o GMP = GMP Whey = GMP, whey = GMP w/o GMP
Hunger and desire to eat: whey and whey w/o GMP < GMP (P < 0.05) Men:
Men: Whey = whey w/o GMP = GMP
Hunger, prospective food consumption and desire to eat: GMP < whey, whey w/o GMP (P < 0.05)
Fullness: GMP > whey w/o GMP (P < 0.05), whey = GMP, whey = whey w/o GMP
Calbet and Holst, 2004 (58) 6 healthy men Crossover (MT) Liquid preloads (600 mL, ∼1000 kJ/L): intact whey, intact casein, WPH, or hydrolyzed casein (all 60 g P/L) GLP-1 and PYY:
(Denmark) Intact whey = intact casein = WPH = hydrolyzed casein
GIP:
20 min: WPH + hydrolyzed casein > intact whey + intact casein (P value NA)
60 min: WPH + hydrolyzed casein < intact whey + intact casein (P value NA)
All time: whey = casein
Diepvens et al., 2008 (67) 39 overweight men and women 2 randomized, single-blind, crossover studies (MT) Study I+II: preloads as shakes (1024 kJ): whey, pea protein hydrolysate, whey + pea protein hydrolysate and milk (all 25 E% P) Ad libitum lunch after 180 min (study II): Study I: GLP-1 (AUC 120 min):
(The Netherlands) whey = pea = whey+pea = milk Hunger: 240 min (AUC): pea < whey and whey+pea (P < 0.05) Pea < milk (P < 0.05), whey = pea = whey+pea
90 min: pea < milk (P < 0.05) CCK (AUC 120 min):
Satiety, fullness, and desire to eat: whey = pea = Milk > pea, whey, and whey+pea (P < 0.05), whey = pea = whey+pea
whey+pea = milk PYY (AUC 120 min):
Study II: Pea = whey = whey+pea = milk
Hunger: whey = pea = whey+pea = milk Ghrelin (AUC 120 min):
Satiety and fullness: Pea = whey = whey+pea = milk
30, 90 min: whey > milk and whey+pea (P < 0.05)
30,60,180 min: pea > milk and whey+pea (P < 0.05)
Hall et al., 2003 (7) Study I: 2 randomized, crossover studies (MT) Liquid preloads (∼1700 kJ): whey or casein (both 48 g P) Ad libitum lunch after 180 min (study I): 180 min (study II): GLP-1 (0–180 min):
(United Kingdom) 16 healthy men and women Casein > whey (P < 0.05) Desire to eat: whey < casein (P < 0.005) Whey > casein (P < 0.05)
Study II: 9 healthy men and women Hunger: whey < casein (P = 0.061) GIP (0–180 min):
Fullness: whey > casein (P < 0.05) Whey > casein (P < 0.005)
CCK (0–180 min):
Whey > casein (P < 0.01)
Hermansen et al., 2005 (88) 100 hypercholesteroleamic men and women Randomized, double-blind (24 wk) Protein supplements included in usual diet (2 sachets/d): soy or casein (both 30 g P/d) 24-h records (0, 24 wk): GLP-1 (iAUC 8 h):
(Denmark) 89 completers Casein = soy Change after 24 wk: soy = casein
GIP (iAUC 8 h):
Increase after 24 wk: soy > casein (P < 0.05)
Hochstenbach-Waelen et al., 2009 (48) 23 healthy men and women Randomized, single-blind, crossover (MT) Protein custards (10 E%/25 E%): casein or gelatin 24 h: GLP-1:
(The Netherlands) Hunger (AAC): 10 E% gelatin > 10 E% casein (P < 0.05), 25 E% gelatin = 25 E% casein Dinner: 10 E% gelatin > 10 E% casein (P < 0.05)
Fullness (AUC): 10+25 E% gelatin = 10+25 E% casein Lunch: 25 E% gelatin > 25 E% casein (P < 0.0001)
PYY:
10+25 E% gelatin = 10+25 E% casein
Ghrelin:
10 E% gelatin = 10 E% casein
25 E% gelatin < 25 E% casein (P < 0.05)
Hochstenbach-Waelen et al., 2010 (52) 81 overweight and obese men and women Randomized, single-blind, parallel (24 wk) Medium milk (wk 9–16: 15 E% P, wk 17–24: 30 E% P) VAS appetite rating in the morning after an overnight fast: GLP-1 and PYY (change from wk 8–16):
(The Netherlands) 72 completed weight loss period, whereas 65 also completed weight maintenance period Phase 1: 8-wk weight loss period (33% of ER), phase 2: 16-wk maintenance period: wk 9–16: complete diet was provided, wk 17–24: 50% of the diet was provided, 50% ad libitum High milk (wk 9–16: 30 E% P, wk 17–24: 60 E% P) Gelatin (50/50% milk protein/gelatin; wk 9–16: 30 E% P, wk 17–24: 60 E% P) Satiety, fullness, hunger, and desire to eat: medium milk = high milk = gelatin Medium milk = high milk = gelatin
Hochstenbach-Waelen et al., 2011 (51) 81 overweight and obese men and women Randomized, single-blind, parallel (8 wk) Medium milk (phase 1: 10 E% P, phase 2: 30 E% P) High milk (phase 1: 20 E% P, phase 2: 60 E% P) Gelatin (50/50% milk protein/gelatin, phase 1: 20 E% P, phase 2: 60 E% P) VAS appetite rating in the morning after an overnight fast: GLP-1 and PYY (change from wk 0–8):
(The Netherlands) 72 completers Phase 1: wk 1–4 100% of ER, Satiety, fullness, hunger, and desire to eat: medium milk = high milk = gelatin Medium milk = high milk = gelatin
Phase 2: wk 5–8 33% of ER
Holmer-Jensen et al., 2012 (65) 11 obese men and women Randomized, controlled, crossover (MT) Milkshakes containing: whey, WPH, αlac, or GMP (all 45 g/19 E% P) GLP-1, GIP, CCK and ghrelin:
(Denmark) Whey = WPH = αlac = GMP
Hursel et al., 2010 (36) 35 healthy men and women Randomized, single-blind, crossover (MT) Breakfast yogurt drinks (15% of ER): whey, αlac (both 41 E% P), or milk (15 E% P) 240 min:
(The Netherlands) Hunger (AAC): αlac < whey (P < 0.05)
Desire to eat (AAC): αlac < whey (P < 0.01)
Fullness and appetite suppression: αlac = whey
Juvonen et al., 2011 (54) 8 normal-weight young men Randomized, crossover (MT) 400-mL preloads (2.4 kJ/g): viscous casein, casein-TG, or whey (all ∼92 E% P) 240 min: GLP-1:
(Finland) Fullness: 15 min: whey > casein-TG (P = 0.074)
15, 30, 120 min: casein-TG > whey (P < 0.05) 30 min: casein > casein-TG (P = 0.074)
30 min: casein-TG > casein (P < 0.05) Whey = casein
All time: whey = casein CCK:
Hunger, desire to eat, and satiety: whey = casein = casein-TG 15 min: whey and casein > casein-TG (P < 0.001)
30 min casein > whey and casein-TG (P < 0.05)
PYY:
Whey = casein = casein-TG
Keogh et al., 2010 (32) 20 overweight and obese men Randomized, double-blind, crossover (MT) 895-kJ preloads containing 50 g of min. GMP, high GMP, whey w/o GMP, or glucose Ad libitum lunch after 180 min: 180 min: CCK:
(Australia) Min. GMP = high GMP = whey w/o GMP Min. GMP = high GMP = whey w/o GMP Min. GMP = high GMP = whey w/o GMP
Lam et al., 2009 (33) 50 healthy men and women Randomized, single-blind, crossover (MT) Liquid preloads as milkshakes (∼1300 kJ): whey w/o GMP, whey including 21% GMP, whey including 21% GMP+GMP (∼45 g P), or CHO (isocaloric) Ad libitum lunch after 30 min: 90 min:
(New Zealand) Whey w/o GMP = whey including 21% GMP = whey including 21% GMP+GMP Whey w/o GMP = whey including 21% GMP = whey including 21% GMP+GMP
Fullness before ad libitum lunch: whey including 21% GMP > whey w/o GMP, whey including 21% GMP+GMP (P < 0.05)
Lang et al., 1998 (44) 12 healthy normal-weight men Nonrandomized, crossover (MT) Test meals (∼5.2 MJ): casein, egg albumin, gelatin, soy, pea, or wheat gluten (all ∼70 g P) 24-h EI: Appetite during 480 min:
(France) Casein = egg albumin = gelatin = soy = pea = gluten Casein = egg albumin = gelatin = soy = pea = gluten
Lang et al., 1999 (45) 9 healthy normal-weight men Nonrandomized, crossover (MT) Test meals (∼1.8 or 3.6 MJ, 23 E% P): casein, gelatin, orsoy (25, 50 g) 24-h EI: Appetite during 480 min:
(France) Casein = gelatin = soy Casein = gelatin = soy
Lorenzen et al., 2012 (46) 22 overweight men Randomized, blinded, crossover (MT) Served as shakes with breakfast (3 MJ): casein, whey, or milk (all ∼34 g P) Ad libitum lunch after 240 min: 240 min:
(Denmark) 17 completers Milk < casein and whey, (P = 0.03), casein = whey Whey = casein = milk
Nieuwenhuizen et al., 2009 (53) 24 healthy men and women Randomized, single-blind, crossover (MT) Breakfast custards (20% of ER ≈2.54 ± 0.06 MJ, 10 E% P): αlac, gelatin, or gelatin+TRP Ad libitum lunch after 180 min: 240 min: GLP-1 and ghrelin (AUC 180 min):
(The Netherlands) αlac = gelatin = gelatin+TRP Hunger AUC: αlac = gelatin = gelatin+TRP αlac = gelatin = gelatin+TRP
At 240 min: αlac < gelatin (P < 0.01) and gelatin+TRP (P < 0.05)
Nilsson et al., 2004 (63) 12 healthy men and women Randomized, controlled, crossover (MT) Breakfasts: white wheat bread, gluten-low (both 2.8 g P), gluten-high, cod, milk, whey, or cheese (casein) (all 18.2 g P) GLP-1 (iAUC 45 min):
(Sweden) Whey = cod = milk = cheese (casein) = white wheat bread (gluten NA)
GIP (iAUC 45 min):
Whey > cod, milk, cheese (casein) and white wheat bread (P < 0.05) (gluten NA)
Nilsson et al., 2007 (64) (Sweden) 12 healthy men and women Randomized, crossover (MT) Breakfast liquid meals (250 mL): glucose (25 g CHO), whey, AA2,4 AA3,4 or AA54 (18 g P) GLP-1 (iAUC 90 min):
Whey = AA2 = AA3 = AA5
GIP (iAUC 90 min):
Whey > AA2, AA3, AA5 (P < 0.05)
Pal and Ellis, 2010 (8) (Australia) 22 healthy lean men Randomized, single-blind, crossover (MT) Liquid preloads (∼1.2 MJ): whey, tuna, turkey, or egg albumin (all 71 E% P) Ad libitum EI after 240 min: whey < tuna, egg, and turkey (P < 0.01) 240 min (iAUC):
Hunger and prospective consumption: whey < tuna (P < 0.03), turkey (P < 0.01), and egg (P < 0.001)
Fullness: whey and tuna > turkey (P < 0.03) and egg (P < 0.001)
Potier et al., 2009 (47) (France) 20 normal-weight women Randomized, crossover (5 d) Solid cheese preloads (∼1000 kJ/100 g): casein, whey+casein (1:2) (both 22 g P), or no preload Ad libitum lunch after 60 min and 24-h EI: casein = whey+casein Appetite before lunch and rest of day:
Casein = whey/casein
Veldhorst et al., 2009 (18) (The Netherlands) 25 healthy men and women Randomized, single-blind, crossover (MT) Breakfast meal custards (20% of ER, 10 E%/25 E% P): whey, casein, or soy Ad libitum meal after 180 min: casein = whey+casein 240 min (AUC): GLP-1 (AUC 180 min):
Hunger: 10 E%: whey < casein (P < 0.05), casein = soy, whey = soy 10 E%: whey = casein = soy
25 E%: whey = casein = soy 25 E%: whey > casein (P < 0.05), whey = soy, casein = soy
Ghrelin (AAC 180 min):
10 E%+25 E%: whey = casein
10 E%: casein < soy (P < 0.05)
Veldhorst et al., 2009 (31) (The Netherlands) 25 healthy men and women Randomized, single-blind, crossover (MT) Breakfast custards (20% of ER, 10 E%/25 E%): whey or whey w/o GMP Ad libitum meal after 180 min: 240 min: GLP-1:
 Whey < whey w/o GMP (P < 0.05) Satiety: 25 E% > 10 E% (P < 0.05)
10 E% > 25 E% (P < 0.05) Whey = whey w/o GMP
Whey = whey w/o GMP Ghrelin:
25E% < 10E% (P < 0.01)
Whey = whey w/o GMP
Veldhorst et al., 2009 (34) (The Netherlands) 24 healthy men and women Randomized, single-blind, crossover (MT) Breakfast custards (20% of ER, 10 E%/25 E% P): casein, soy, whey, whey w/o GMP, αlac, gelatin, or gelatin+TRP Ad libitum meal after 180 min: 180 min: GLP-1:
10 E%+25 E%: αlac, gelatin, and gelatin+TRP < casein, soy, and whey w/o GMP (P < 0.05), 25 E%: αlac and gelatin+TRP < whey (P < 0.05) Satiety: 10 E%+25 E%: αlac, gelatin, and gelatin+TRP > casein, soy, whey, and whey w/o GMP (P < 0.05) 10 E%: casein = soy = whey = whey w/o GMP = αlac = gelatin = gelatin+TRP
25 E%: gelatin+TRP > casein and soy (P < 0.05)
Ghrelin:
10 E%+25 E%: casein = soy = whey = whey w/o GMP = αlac = gelatin = gelatin+TRP
1

AAC, area above the curve; αlac, α-lactalbumin; AUC, area under the curve; BW, body weight; casein-TG gel, casein cross-linked by transglutaminase; CCK, cholecystokinin; CHO, carbohydrate; E%, energy percent; EI, energy intake; ER, daily energy requirement; GI, gastrointestinal; GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide 1; GMP, glycomacropeptide; high GMP, glycosylated GMP; iAUC, incremental AUC; min. GMP, minimally glycosylated GMP; NA, not applicable; P, protein; PYY, peptide YY; TRP, tryptophan; VAS, visual analogue scales; WPH, whey protein hydrolysate; w/o, without.

2

Selected outcomes; for all outcomes, see original papers.

3

MT includes both preload and meal test studies.

4

AA2, 1.6 g lysine, 1.4 g threonine; AA3, 2.2 g leucine, 1.1 g isoleucine, 1.1 g valine; AA5, 2.2 g leucine, 1.1 g isoleucine, 1.1 g, valine, 1.6 g lysine, 1.4 g threonine.

Table 2.

Controlled clinical trials with energy expenditure as outcome1

Intervention
Outcome2
Reference Population Design Diet/supplement TEE DIT Substrate balances
Acheson et al., 2011 (9) (Switzerland) 23 lean men and women Randomized, double-blind, crossover Meals (shakes) – energy density 1 kcal/g (459 kcal): whey, casein, soy (all 50 E% P), or CHO (isocaloric) Whey > casein (P = 0.002) Fat oxidation: casein = whey, casein = soy, whey > soy (P = 0.098)
Duration: 330 min Whey > soy (P = 0.001)
Whey = casein
Alfenas et al., 2010 (42) 26 normal weight men and women Randomized, crossover Served as breakfast on 7 consecutive days, 0.5 g P/kg BW (∼265 kcal): whey, casein, soy (∼25 g P), or control (∼8.5 g P) Whey = casein RQ: whey = casein, whey < soy, (day 7, P < 0.05)
(Brazil) 24 completed the first 3 sessions, only 10 completed the soy session Duration: 7 d (DIT: 60 min) Soy > whey (day 7, P = 0.024)
Hochstenbach-Waelen et al., 2009 (48) 23 healthy men and women Randomized, single -blind, crossover Served as breakfast custards (20% of ER, 10 E%/25 E%): casein or gelatin 10 E% + 25 E%: casein = gelatin 10 E% + 25 E%: casein = gelatin Protein balance: 10 E% (negative): casein < gelatin (P < 0.05), 25 E% (positive):
(The Netherlands) Duration: 36 h (DIT: 24 h) casein > gelatin (P < 0.0001)
Protein oxidation: casein < gelatin (10 E%, P < 0.05, 25 E%, P < 0.0001)
RQ: 10+25 E%: casein = gelatin
Hursel et al., 2010 (36) 35 healthy men and women Randomized, single-blind, crossover Breakfast yogurt drinks (15% of ER): whey, αlac (both 41 E% P) or milk (15 E% P) Whey = αlac Protein balance: whey = αlac
(The Netherlands) Duration: 240 min RQ: whey = αlac
Karst et al., 1984 (71) Study I: Crossover Served as shakes: egg, gelatin, casein, or starch (all 1 MJ) Casein > gelatin and starch (P < 0.01)
(Germany) 5 healthy normal weight men Duration: 360 min Casein = egg
Lorenzen et al., 2012 (46) 22 overweight men Randomized, blinded, crossover Served as shakes with breakfast (3 MJ): casein, whey, or milk (all ∼34 g P) Whey = casein = milk protein Fat oxidation:
(Denmark) 17 completers Duration: 240 min Casein > whey (P = 0.015)
casein = milk
whey = milk
1

αlac, α-lactalbumin; BW, body weight; CHO, carbohydrate; DIT, diet-induced thermogenesis; E%, energy percent; ER, daily energy requirements; P, protein; RQ, respiratory quotient; TEE, total energy expenditure.

2

Selected outcomes; for all outcomes, see original papers.

Table 3.

Controlled clinical trials with body weight or body composition as outcome1

Reference Population Intervention
Outcome2
Design Diet/supplement BW FM/ %FM FFM/%FFM/lean mass
Exercise programs
Colker et al., 2000 (75) 16 athletic men Randomized, double-blind (10 wk) Protein from food could not exceed 1.6 g/kg/d. In addition, supplements were added: whey (whey concentrate 30 g/d + whey isolate 10 g/d), or whey+BCAA+glutamine (whey concentrate 30 g/d and whey isolate 10 g/d, l-glutamine 5 g/d, BCAA (leucine 1.5 g/d, isoleucine 0.75 g/d, valine 0.75 g/d)) Greater increase for whey+BCAA+glutamine group than whey (P < 0.05) %FM: significant decrease in both groups FFM: tendency for greater increase for whey+BCAA+glutamine than whey (P = 0.09)
(USA) All completers Resistance training program (3 times/wk) NS between groups
Cribb et al., 2006 (74) 19 men Randomized, double-blind parallel (10 wk) Supplements added to usual diet (1.5 g supplement · kg−1 · d−1): WPH or intact casein (∼90 g P) FM: greater decrease for whey than casein, NS (P value NA) Lean mass: g reater increase for whey than casein (P < 0.01)
(Australia) 13 completers Resistance training program (3 times/wk)
Demling and DeSanti, 2000 (19) 38 overweight men Randomized, parallel Hypocaloric diet (80% of estimated food intake): hydrolyzed casein, WPH (both resistance training + 70–75 g P/d), or control (all hypocaloric diet) Significant decrease for both whey and casein FM: greater decrease for casein than whey (P < 0.05) FFM: greater increase for casein than whey (P < 0.05)
(United Kingdom) 32 completers (12 wk) NS between groups
Resistance training program (4 times/wk)
Kerksick et al., 2006 (76) 36 healthy men Randomized, double-blind (10 wk) Supplements added to usual diet: Significant increase in whey+casein group FM: no significant change in any groups FFM + lean mass: greater increase for whey+casein than whey+BCAA
(USA) Completers uncertain Resistance training program (4 times/wk) whey+BCAA+glutamine (40 g/d+3 g/d+5 g/d), whey+casein (40 g/d+8 g/d), or CHO (48 g/d CHO) NS between groups NS between groups +glutamine (P < 0.05)
Lollo et al., 2011 (78) 24 young professional soccer players (men) Double-blind, parallel Subjects were housed and fed under the same condition. Protein supplement 1 g/kg/d after the daily training session: whey, WPH (degree of hydrolysis: 10.5%), or casein (all ∼90% P) No significant change in any groups %FM: decreased in WPH (P < 0.05) FFM: increased in casein group (P < 0.05)
(Brazil) Average work load: 1–2 games/wk and 6–8 training session/wk of 2.5 h (8 wk) No change in the whey and casein groups. No change in the whey and WPH groups
Energy-restricted diets
Anderson et al., 2005 (80) 90 obese men and women Randomized, parallel Energy-reduced diet (1200 kcal/d): milk (13 g P) or soy (18 g P) Significant decrease in both groups
(USA) 52 completers (12 wk) NS between groups
Anderson et al., 2007 (81) 43 obese women Randomized, single-blind, parallel Energy-reduced diet (4.5–5.0 MJ/d): soy+isoflavones or casein (both ∼20 g P) Significant decrease in both groups FM: significant decreased in both groups Lean mass: significant increase in both groups NS between groups
(USA) 35 completers (16 wk) NS between groups NS between groups
Faghih et al., 2011 (11) 100 overweight and obese women Randomized (8 wk) Energy-reduced diet (500 kcal/d energy deficit): control (500–600 mg Ca/d), calcium (800 mg Ca/d), milk (3 × 220 mL milk/d including 1200–1300 mg Ca/d), or soy (3 × 220 mL soy milk/d fortified with 1200–1300 mg Ca/d) Greater decrease for milk than soy milk (P < 0.05), calcium (P < 0.01), and control (P < 0.01) %FM: significant decrease in all groups
(Iran) 85 completers NS between groups
Hochstenbach-Waelen et al., 2011 (51) 81 overweight and obese men and women Randomized, single-blind, parallel (8 wk) Medium milk (phase 1: 10 E% P, phase 2: 30 E% P) Phase 1+2: significant decrease in all groups FM and %FM: phase 1+2: significant decrease in all groups FFM: phase 1+2:
(The Netherlands) 72 completers Phase 1: wk 1–4, 100% of ER, phase 2: wk 5–8, 33% of ER High milk (phase 1: 20 E% P, phase 2: 60 E% P) NS between groups NS between groups Significant decrease in all groups
Gelatin (50/50% milk protein/gelatin, phase 1: 20 E% P, phase 2: 60 E% P) NS between groups
FFM as % BW: phases 1+2: significant increase in all groups NS between group
Keogh and Clifton, 2008 (84) 127 overweight and obese men and women Randomized, double-blind, parallel (12 mo) Energy-reduced diet (exact energy intake NA): 90% GMP or milk (both 15 g P) Significant decrease in both groups FM: significant decrease in both groups Lean mass: significant decrease in both groups
(Australia) 72 completers Phase 1: 2 shakes/d, 6 mo, phase 2: 1 shake/d, 6 mo NS between groups NS between groups NS between groups
Soenen et al., 2010 (82) 87 overweight and obese men and women Randomized, parallel (6 mo) αlac (50/50 mix of αlac and milk protein; phase 1: 20 E% P, phase 2: 60 E% P, phase 3: 30 E% P) Significant decrease in all groups FM: significant decrease in all groups FFM: decreased only in medium milk group (P < 0.05)
(The Netherlands) 72 completers Phase 1: 1 mo, 100% EI as meal replacement; phase 2: 1 mo, 33% of EI as meal replacement; phase 3: 2 mo, 67% EI as meal replacement; phase 4: 2 mo, 33% EI as meal replacement + 33% EI ad libitum High milk (phase 1: 20 E% P, phase 2: 60 E% P, phase 3: 30 E% P) NS between groups NS between groups NS between groups
Medium milk (phase 1: 10 E% P, phase 2: 30 E% P, phase 3: 15 E% P)
Weight maintenance
Baer et al., 2011 (43) 90 overweight and obese men and women Randomized, double-blind (23 wk) Supplements, 2 packets/d (1670 kJ/d) included in usual diet: whey, soy (both ∼28 g P/packet), or CHO (isocaloric) No significant change in any groups, but greater decrease with whey than CHO (P < 0.006) FM: greater decrease for whey than CHO (P < 0.005) Lean mass: no significant change in any groups
(USA) 73 completers NS between whey and soy NS between whey and soy NS between groups
Claessens et al., 2009 (86) 60 overweight and obese men and women Randomized, parallel (blinded to the type of protein) (17 wk) Phase 2: weight maintenance: whey, casein, or CHO (50 g/d) Phase 2: greater decrease for whey and casein than CHO (P = 0.04) FM: phase 2: greater decrease for whey and casein than CHO (P = 0.02) FFM: phase 2: trend for greater increase for whey than casein (P = 0.09)
(The Netherlands) 48 completers Phase 1: 5-wk liquid diet (500 kcal/d) NS between whey and casein NS between whey and casein
Phase 2: 12-wk weight maintenance, ad libitum EI
Hochstenbach-Waelen et al., 2010 (52) 81 overweight and obese men and women Randomized, single-blind, parallel (24 wk) Medium milk (wk 9–16: 15 E% P; wk 17–24: 30 E% P) Phases 1+2: significantly decreased in all groups during weight loss and sustained during weight maintenance FM: phase 2: no significant change in any groups FFM: phase 2: no significant change in any group
(The Netherlands) 72 completed weight-loss period, whereas 65 also completed weight maintenance period Phase 1: 8 wk, weight-loss period (33% of EI), phase 2: 16-wk maintenance period: wk 9–16: complete diet was provided, wk 17–24: 50% of the diet was provided, 50% ad libitum High milk (wk 9–16: 30 E% P; wk 17–24: 60 E% P) NS between groups NS between groups NS between groups
Gelatin (50/50% milk protein/gelatin; wk 9–16: 30 E% P, wk 17–24: 60 E% P)
Takahira et al., 2011 (87) (Japan) 48 men and women with visceral fat area > 100 cm2 Randomized, double-blind, parallel (20 wk) Usual diet: milk (21.9 g/d) or soy (12 g soy+9.25 g milk/d) 20 wk: decreased only in milk group (P < 0.01) Visceral fat area:
43 completers greater decrease for milk than soy (P value NA)
1

αlac, α-lactalbumin; BCAA, branch-chained amino acids; BW, body weight; Ca, calcium; CHO, carbohydrate; E%, energy percent; EI, energy intake; ER, daily energy requirement; FFM, fat free mass; FM, fat mass; GMP, glycomacropeptide; NA, not applicable; NS, nonsignificant; P, protein; WPH, whey protein hydrolysate.

2

Selected outcomes; for all outcomes, see original papers.

Appetite

Protein is more satiating than fat and carbohydrate (5, 2027), but the effect may be source dependent. Several studies have examined the appetite-regulating effect of proteins (Table 1). No clear evidence exists that 1 protein source is more satiating than others. However, discrepant results may be explained by different study designs, including timing of measurements, protein structure, and food texture. Whey consumption has shown promising effects in several health aspects, such as obesity and type 2 diabetes (28), and it could be speculated that part of this effect is due to the satiating effect of whey. The satiating effect of whey has been examined and compared with that of casein and other protein sources in several studies using a visual analogue scale (VAS), ad libitum energy intake, and measurement of postprandial GI hormone responses (Table 1).

Protein quality

The most important factor determining protein quality is its amino acid composition. Whey has a high content of essential and branched-chain amino acids (BCAAs), which is likely the reason that it is highly effective at promoting protein synthesis (29). In addition, whey contains the bioactive components glycomacropeptide (GMP), αlac, and other minor abundant components such as lactoferrin and lactoperoxidase. GMP is a carbohydrate-containing peptide derived from κ-casein during cheese making and extracted into the whey fraction. It has a high content of BCAAs and is potentially an effective secretagogue of cholecystokinin (CCK), which is secreted in the gut in response to food intake and acts as a satiety signal (30). In accordance, Veldhorst et al. (31) demonstrated an increased energy intake after consumption of a GMP-depleted whey supplement compared with consumption of whey alone. However, most data on subjective feelings of appetite indicate that GMP is not critical for whey-induced satiety (3034) or for whey induced decreases in energy intake (30, 32, 33).

The fraction of αlac makes up ∼20% of whey (14) and 3.4% of total protein in bovine milk (35). It has been hypothesized that αlac has a beneficial effect on satiety owing to a high content of essential amino acids such as leucine, lysine, and tryptophan (3537). Tryptophan is a precursor of the neurotransmitter serotonin, which acts as an anorexigenic signal in the brain stimulating satiety. Leucine and lysine are ketogenic amino acids, and it has been shown that appetite decreases under ketogenic conditions (21). In support, data on αlac indicate a satiating effect beyond that of whey when appetite measures are obtained by VAS (34, 36) and ad libitum energy intake 180 min after protein consumption (34). However, only a few studies have been conducted, and it is still not clear whether the effect persists over time.

Furthermore, whey has been found to increase satiety compared with protein from tuna, turkey (8), and egg (8, 38) when measured by VAS or ad libitum energy intake. In addition to whey, casein is also a complete protein. Moreover, soy is often classified as a complete protein, despite a much lower content of essential amino acids than the dairy proteins (39). As shown in Table 1, data from several studies indicate no difference in satiety between these 3 proteins in both acute and long-term settings (34, 4047). However, Veldhorst et al. (18) studied the appetite-regulating effects of whey, casein, and soy at 10 energy percent (E%) and 25 E% from protein given as custards at breakfast. They found whey to decrease hunger compared with casein and soy at the low dose, but they observed no difference at the high dose. Moreover, there was no difference between casein and soy at both doses, and ad libitum energy intake did not differ between any of the proteins. Veldhorst et al. (18) propose that the concentration of certain amino acids needs to be above a particular threshold to promote a relatively stronger hunger suppression or greater satiety. Their results suggest that certain proteins will reach these threshold concentrations at lower concentrations than other sources of proteins. At high protein concentrations, it may not be possible to discriminate between complete proteins because the amino acid concentrations are above the threshold for all protein sources. In most of the studies comparing whey, casein, and soy, the protein concentration is >10 E% (Table 1), which may partly explain why no differences in satiety measures are observed.

In contrast, it has been suggested that incomplete proteins may be more satiating than complete proteins in the acute setting (48). According to that hypothesis, consumption of diets low in essential amino acids will induce a decrease in plasma concentration of these amino acids, which in rodents is found to be detected in the brain and lead to a behavioral response rejecting consumption of imbalanced diets and consequently a suppression of hunger (49, 50). The satiating effect of whey, casein, and soy has been compared with the incomplete protein gelatin in a few studies (Table 1) (34, 44, 45, 48). Two studies by Lang et al. (44, 45) observed no difference in appetite between proteins in the acute settings, but, in contrast, Hochstenbach-Waelen et al. (48) demonstrated a hunger-suppressing effect of gelatin compared with casein at a low (10 E%) protein dose, and Veldhorst et al. (34) found gelatin to increase satiety compared with casein and whey, independent of protein dose. A limitation of the studies by Lang et al. (44, 45) is that protein meals were not completely identical in macronutrient and energy composition. Moreover, proteins were not consumed as supplements, but as mixed meals with varying fiber content, which may have blunted the potential differences between different protein sources (44). In addition, only 12 (44) and 9 (45) subjects were included. The decreased hunger feelings with consumption of gelatin observed by Hochtenbach-Waelen et al. (48) may have been understood as an anorexigenic effect of intake of food lacking essential amino acids. After consumption of the 10 E% gelatin breakfast, the plasma concentrations of the essential amino acids histidine, valine, methionine, isoleucine, phenylalanine, tryptophan, and leucine decreased and were lower than after casein consumption. Under the 25 E% conditions, only the plasma concentration of tryptophan decreased and was lower after consumption of the gelatin compared with the casein breakfast (34, 48). This does not, however, seem to play a role in the long term. When appetite was recorded over several weeks, there was no difference in appetite regulation between gelatin and milk (51, 52). Furthermore, data from Nieuwenhuizen et al. (53) indicate that tryptophan alone may not play a very important role in appetite regulation as no difference in subjective feelings of satiety and ad libitum energy intake was observed between gelatin and gelatin with added tryptophan. However, tryptophan may be important in combination with other essential amino acids.

Digestion and absorption rate

Besides differences in amino acid composition, proteins differ in digestion and absorption rates, which may be important with regard to appetite regulation. It is well-known that whey and casein differ in absorption rate, with whey being absorbed rapidly and casein slowly as it coagulates in the acidic environment in the stomach (17). The satiating effect of the 2 proteins have been compared in few studies, most of which were acute studies (7, 9, 18, 40, 42, 46, 47, 54) (Table 1) showing no clear evidence that 1 protein is more satiating than the other.

Hall et al. (7) showed that whey was more satiating when subjective appetite sensations were recorded for 180 min, and, in accordance, whey was more efficient at decreasing energy intake at an ad libitum lunch buffet served 90 min after preload consumption compared with casein. In contrast, casein has been shown to be more satiating than whey when subjective appetite measures were continued for 330 min (9). These results suggest that timing of appetite measures may be important and that the effects of casein may not be fully developed when appetite measures are obtained shortly (90–180 min) after preload consumption. Additionally, when appetite measures are obtained several hours (330 min) after protein consumption, as in the Acheson study (9), the concentration of amino acids after whey consumption may have reached baseline. Previous studies support this (17, 55). It has been shown that plasma amino acid concentrations were higher after whey compared with casein 100 min after protein ingestion and vice versa 300 min after protein ingestion (17). Likewise, Dangin et al. (55) showed that a free amino acid mixture matched to casein (fast digestion rate) and whey induced a fast and transient increase in amino acids, whereas intact casein and whey given in small boluses to mimic a slow digestion rate gave rise to prolonged and maintained plasma amino acid concentrations. Moreover, Dangin et al. (55) showed that a slower digestion rate favors greater whole-body protein balance, at least over rapidly digested proteins. The meals were matched for nitrogen and leucine content, and the results therefore support that digestion rate is an independent factor regulating protein kinetics (55).

Therefore, all of these data could indicate that the “fast” protein whey is more satiating than the “slow” protein casein in the short term and vice versa in the long term, which may partly be explained by the difference in the rate of amino acid appearance in the blood and the postprandial secretion of GI hormones. Alfenas et al. (42) support the finding that casein is more satiating than whey in the long term. Casein was found to reduce daily energy intake compared with whey during a 7-d supplementation period. Additionally, casein supplementation induced a lower energy intake on day 7 compared with day 1.

Addition of energy from carbohydrate and fat

In studies with focus on appetite, proteins are rarely served free of energy from carbohydrate and fat. This may mask the difference in protein kinetics observed for casein and whey and thereby partly explain why a difference in the satiating effect of whey and casein has not been observed in all studies.

Dangin et al. (56) showed that in young adults, the differences in the rate of amino acid appearance in the blood were less pronounced when whey and casein were consumed with added energy from carbohydrate and fat. This was mostly due to a slower absorption of whey when carbohydrate and fat were added. However, the increase in plasma amino acids was still faster for whey than casein (56). Moreover, the more beneficial effect of casein compared with whey on protein balance when given alone (17) was reserved when energy from carbohydrate and fat was added (56). Protein synthesis was not affected, but protein breakdown was highly decreased after whey consumption and slightly decreased after casein consumption (no difference between proteins) (56). The less pronounced decrease with casein may be explained by its already present depression of protein breakdown when consumed alone (17), which may be explained by prolonged hyperaminoacidemia. However, other factors such as protein structure and secretion of GI hormones most likely also play a role in protein-induced satiety.

Protein structure

Protein structure may influence the absorption rate and thereby play an important role in a protein’s ability to stimulate satiety. Proteins can be broken down into smaller peptide fractions and free amino acids by exogenous hydrolysis, which thereby potentially induces an increased digestion and absorption rate of the protein (57). Calbet and Holst (58) demonstrated that hydrolyzed casein was absorbed more rapidly than intact casein and that the absorption rate of hydrolyzed casein approached the rate of whey. In contrast, they observed similar intestinal absorption rates of intact whey and its hydrolysate. This is, however, not a consistent finding (59). Moreover, when examining the effects on appetite regulation, hydrolysis of whey seems to be of less importance (38, 60). This may be explained by the fast absorption and digestion of intact whey protein. Mahé et al. (61) showed that β-lactoglobulin, a main component of whey, was rapidly recovered in the upper intestine mostly in the form of intact protein that needs to be further degraded to be absorbed more distally. In contrast, casein was slowly recovered in the jejunum, mainly in the form of degraded peptides efficiently absorbed in the upper part of the intestine (61). These differences in absorption kinetics may be explained by the different structure of the 2 proteins. As previously described, casein exists as micelles, which, in addition to casein, contains water and salts. The caseins are hydrophobic, but κ-casein contains the hydrophilic component GMP, which stabilizes the micelle. In contrast, whey proteins are soluble and remain soluble in the stomach, which is why they reach the upper intestine more rapidly than casein (61). The impact of protein hydrolysis on satiety may consequently be different for casein, but this has to our knowledge not yet been investigated.

Another aspect, which should be taken into consideration when measuring appetite sensations, is that the initiation of an eating episode does not wholly rely on hunger sensations. The sensory properties of a food item can stimulate food intake even when satiety signals are present (7). Hall et al. (7) proposed that if protein preloads are administered as a liquid meal rather than a more customary solid meal, the cognitive and sensory stimuli that normally inhibit the desire to eat will be repressed until the consumption of a more familiar solid meal, such as the standard lunch buffet.

This was supported by Juvonen et al. (54), who recently showed that gelation of casein by cross-linking with transglutaminase resulted in increased subjective feelings of fullness compared with viscous casein and liquid whey. However, no treatment effects were observed in hunger, the desire to eat, and satiety (Table 1). Moreover, it should be noted that the palatability of the test meals was much lower for the gel-based casein than for casein and whey. It could therefore be speculated that the increased fullness observed with the casein gel was associated with the poor palatability and not only the texture of the protein. However, it is known that an increase in the viscosity or firmness of a food item delays gastric emptying (54). Future studies are needed to determine the effect of food texture and protein structure when comparing the satiating effects of different proteins.

GI hormones

Hormones are secreted in response to food intake from specialized enteroendocrine cells throughout the GI tract. The overall function of the GI hormones is to regulate food intake, either by inducing hunger (ghrelin) or satiety [CCK, glucagon-like peptide 1 (GLP-1), peptide YY (PYY)] and/or to stabilize postprandial glucose excursions [the incretin hormones GLP-1 and glucose-dependent insulinotropic polypeptide (GIP)] (62). Thus, the effects of ingested macronutrients on appetite may in part be mediated by postprandial GI hormone responses.

In some, but not all, studies, whey has been found to stimulate 1 or both of the incretin hormones to a greater extent than other protein sources, such as casein, milk, cod (7, 18, 63), and specific combinations of the essential amino acids: leucine, isoleucine, lysine, valine, and threonine (64). However, in other studies, no difference was observed between whey and casein (34, 58). Additionally, Holmer-Jensen et al. (65) found no difference in plasma levels of GLP-1 and GIP between whey and specific whey components (hydrolyzed whey, αlac, and GMP).

In accordance with a more satiating effect of whey compared with casein, Hall et al. (7) demonstrated a larger increase in GLP-1, GIP, and CCK after whey consumption, suggesting that the satiating effect of whey at least in part was mediated through GI hormones. In addition, the secretion profiles over time (0–180 min) were somewhat different for the 3 hormones. This possibly mirrors the different localizations of the different endocrine cell types (66) but may also suggest differences in the mechanisms behind the observed effects. Contrary, postprandial hormone responses do not always translate into satiety. In the study by Juvonen et al. (54), the effect on fullness (Table 1) was unlikely to be caused by alterations in the secretion of satiating hormones. Postprandial CCK response was significantly greater after liquid whey and viscous casein consumption compared with the gel-based casein, whereas fullness was greater after consumption of the gel-based casein compared with whey and casein. Likewise, a similar trend (P = 0.074) was observed for GLP-1. Veldhorst et al. (18) support the finding that the secretion of GI hormones does not always translate into a more satiating effect of a given protein. In their study, they observed no difference in postprandial GLP-1 response after intake of whey and casein given at 10 E%, but at 25 E% from protein, postprandial GLP-1 response was greater after whey consumption compared with casein. This is in contrast to the findings on appetite, where it was only possible to detect a difference at the low protein dose. For ghrelin and PYY secretion, no clear evidence exists that 1 protein source induces higher postprandial responses than other protein sources (34, 40, 41, 48, 54, 58, 67) (Table 1).

Few studies have looked at the effect of protein hydrolysis. Holmer-Jensen et al. (65) demonstrated similar concentrations of GLP-1, GIP, CCK, and ghrelin after consumption of whey protein isolate and hydrolyzed whey. In the study by Calbet and Holst (58), whey, casein, and their hydrolysates elicited a similar concentration of GLP-1 and PYY. GIP secretion was greater for the hydrolysates than for the intact proteins during the first 20 min and less after 60 min (58). None of these studies examined the association with appetite regulation, but for whey and its hydrolysate, the findings are in accord with findings on appetite in other studies (38, 60).

In summary, no clear evidence exists that 1 protein source is more satiating than others. However, the “fast” protein whey seems to be more satiating than the “slow” protein casein in the short term and vice versa in the long term. Additionally, data indicate that protein quality and protein kinetics may be important factors in appetite regulation. Finally, there is no clear evidence that secretion of GI hormones is directly translated into greater satiety, and no clear evidence that 1 protein source elicit greater postprandial GI responses than others.

Energy expenditure

Diet-induced thermogenesis

In addition to the satiating effect of protein, it is well documented that DIT is greater for protein (20–35% of ingested energy) than carbohydrate (5–15% of ingested energy) and fat (0–3% of ingested energy) (4, 68, 69). DIT is the increase in energy expenditure above baseline after food consumption, which represents the energy required primarily for digestion, absorption, and disposal of ingested nutrients (68). The high thermogenesis of protein may be explained by the lack of storage capacity in the body, the high ATP cost of protein synthesis, and the metabolic costs of urea synthesis (70). Because proteins vary in amino acids and their effect on protein synthesis, it can be speculated that protein from different sources have different effects on DIT, but only sparse information is available (Table 2) (4). Few studies have examined the effects of whey and casein on DIT. Acheson et al. (9) found whey to increase DIT to a greater extent than casein. They propose that the difference in the rate of body protein synthesis after whey or casein consumption may explain the observed difference in DIT. Boirie et al. (17) showed that protein synthesis was 2-fold more rapid, measured 40–140 min, after consumption of whey compared with casein. In contrast, others have not been able to show any difference in DIT between whey and casein (28, 31). However, a small study supports the finding that DIT depends on protein source (71). Karst et al. (71) demonstrated a higher DIT after casein consumption compared with consumption of isocaloric shakes of egg protein and gelatin. In contrast, Hochstenbach-Waelen et al. (48) observed no difference in DIT after casein or gelatin consumption, and Hursel et al. (36) were not able to show a difference in DIT between whey and αlac. Furthermore, the findings on DIT are not always in accord with the findings on appetite. Acheson et al. (9) found that casein was more satiating than whey, but that whey stimulated DIT to a greater extent than casein, whereas Hursel et al. (36) found αlac to suppress hunger more than whey, whereas they observed no difference in DIT. This may indicate that different mechanisms come into play when examining appetite regulation and energy expenditure.

Lipid oxidation

In addition to the effects on DIT, protein-induced lipid oxidation was also examined by Lorenzen et al. (46) and Acheson et al. (9). Lorenzen et al. (46) observed a small increase in lipid oxidation after casein consumption compared with whey, but, in contrast, Acheson et al. (9) observed no difference between the 2 proteins. However, they observed a tendency for whey to stimulate a greater lipid oxidation than soy. To our knowledge, these are the first studies to investigate lipid oxidation induced differences between casein and whey. In addition, 1 study has examined the effects on the respiratory quotient (RQ), an indicator of lipid oxidation (42). It supports that whey and casein have a similar RQ and that the RQ is lower after whey consumption compared with soy (42). The increased lipid oxidation after consumption of casein compared with whey observed by Lorenzen et al. (46) may be due to differences in postprandial insulin response, but this was not measured. Insulin is known to suppress lipid oxidation why a lower postprandial increase in insulin would be expected to induce a higher postprandial lipid oxidation. However, the study by Acheson et al. (9) does not support this notion. Although, Acheson et al. (9) did not observe any difference in lipid oxidation between casein and whey, they observed a lower postprandial insulin response after casein consumption compared with whey. Also, postprandial insulin responses were similar between whey and soy, despite a tendency for a greater lipid oxidation after whey consumption. Other mechanisms must therefore be involved, and this needs further investigation in future studies.

Body weight and composition

Increased satiety and energy expenditure observed with consumption of high-protein diets may translate into beneficial effects on body weight and composition over time. A recent review examined the hypothesis that different protein sources affect body weight and composition to different extents (6). They concluded that there was no clear evidence that 1 protein source was preferable over other sources, but that animal protein, especially from dairy, was better at promoting protein synthesis than plant proteins. This may be because amino acids from dairy products are used to a lesser extent for splanchnic catabolic activity and to a greater extent for peripheral anabolic activity than plant proteins (72). Because of protein’s anabolic activities, caused by increased muscle protein synthesis, bodybuilders and athletes often consume protein supplements with the purpose of increasing lean body mass. Moreover, proteins are found to be beneficial in weight-reducing programs because they help preserve lean body mass (73).

Exercise programs

As described previously, proteins high in BCAA and other essential amino acids are proteins of high quality, which are more effective at promoting protein synthesis than proteins low in essential amino acids (29). In addition to protein quality, the results obtained from resistance training combined with protein supplementation may depend on the rates of absorption and unique hormonal responses, such as secretion of insulin (74). Colker et al. (75) demonstrated a greater increase in body weight (P < 0.05) and lean body mass (P = 0.09) (Table 3) when adding BCAA and glutamine to whey compared with whey alone. Moreover, Kerksick et al. (76) showed a superior effect of whey and casein compared with whey, BCAA, and glutamine, which support that supplementation with proteins of higher quality promotes protein synthesis and thereby increases lean body mass. Consumption of whey primarily stimulates protein synthesis, whereas consumption of casein primarily inhibits protein breakdown (17, 39). This may explain the beneficial effects on lean body mass observed when the 2 proteins are combined.

Casein appears to produce a greater protein balance than whey (17). However, when whey and casein are consumed with other sources of energy, whey appears to stimulate a greater protein balance than casein (56). The latter is important because athletes rarely consume protein supplements free of other energy sources. Likewise, it has been shown that muscle protein synthesis is higher at rest and after exercise after consumption of hydrolyzed whey compared with micellar casein (77), possibly because of the difference in protein kinetics or because whey induced a higher plasma concentration of leucine than casein (77). Cribb et al. (74) support this because they found a whey protein hydrolysate to reduce fat mass (NS) and increase lean body mass to a greater extent than casein (Table 3). In contrast, Demling and DeSanti (19) found hydrolyzed casein to decrease body fat mass and increase lean body mass to a greater extent than hydrolyzed whey. Moreover, they observed a tendency toward a greater loss of body weight with casein compared with whey supplementation. This supports the finding by Calbet and Holst (58) that hydrolysis affects casein kinetics and thereby potentially the results on body weight and body composition. However, a recent study by Lollo et al. (78) showed that intact casein was superior to both intact and hydrolyzed whey in increasing muscle mass in professional soccer players (Table 3).

Energy-restricted diets

Proteins are found to inhibit loss of lean body mass during energy restriction (73, 79), presumably due to a positive protein balance. Moreover, proteins are found to induce greater weight and fat mass loss than carbohydrates (73). As casein and whey differ in their effect on protein balance, it could be speculated that dissimilar effects will be found when proteins are added to weight loss programs. Unfortunately, we are not aware of any human studies comparing the weight loss–inducing effects of whey and casein during energy restriction, but few studies have investigated the body weight–reducing effects of milk or dairy protein (combination of casein and whey) compared with other protein sources (Table 3). Faghih et al. (11) found milk to induce a greater reduction in body weight and central obesity than soy milk fortified with calcium during an 8-wk period. In contrast, Anderson and Hoie (80) observed no difference in body weight loss between soy and milk supplementation during 12 wk of energy restriction. In this study, it should, however, be noted that the soy protein was consumed more often than the dairy protein, which resulted in a higher dose of soy protein (Table 3). Data might have been different if the supplements had been isocaloric and if the subjects had consumed the same daily quantity of protein. Furthermore, in a study by Hochstenbach-Waelen et al. (48), gelatin was found to suppress hunger, but when gelatin was added to milk and compared with milk alone, no body weight–reducing difference was observed (51). The anorexigenic effect of gelatin did therefore not seem to translate into a beneficial effect on body weight when mixed with dairy protein compared with dairy protein alone.

In another study, Anderson et al. (81) examined the effects of casein and soy combined with energy restriction on body weight and composition (Table 3). Both proteins resulted in similar reductions in body weight and fat mass and similar increases in lean body mass. The result that soy and casein induce similar long-term effects on body weight is in line with the acute findings on appetite by Lang et al. (44, 45).

With regard to studies on appetite regulation, the whey components αlac and GMP are suggested to have beneficial effects on body weight. Few short-term studies have found αlac to be more satiating than whey (34, 36). To our knowledge, the long-term effects of αlac on body weight in humans have only been examined in 1 study, which did not find αlac to be superior to milk with regard to effects on body weight and composition (82) (Table 3). However, energy intake was highly regulated, and a potential effect of αlac on appetite regulation was probably not possible to detect, which might explain the missing effect on body weight and composition. Pilvi et al. (83) found that during energy restriction, αlac reduced body fat mass to a greater extent than whey in obese mice. Because αlac has beneficial short-term effects on appetite and animal studies indicate a beneficial effect on body fat mass, more human studies to elucidate the long-term effects on body weight and composition are needed.

Keogh and Clifton (84) examined the effects on body composition of isocaloric shakes of GMP or skimmed milk (Table 3). They observed no difference in loss of body weight or fat mass or gain in lean body mass between groups. The observation that GMP adds no extra effect to milk is in line with the overall findings observed when looking at acute responses on energy intake or subjective sensations of appetite (3032, 34). On the other hand, results from a study in rats indicated a beneficial effect of GMP when looking at the effects on body fat accumulation (85). However, when examining the effect on body weight, whey seemed to be more beneficial than GMP. The GMP dose used in the rat study was much greater than that used in the human study, and it could be speculated that a higher dose of GMP might also be beneficial for humans.

Weight maintenance

Data published from the Diet Obesity and Genes (DiOGenes) study showed that a high protein/low glycemic index diet was beneficial in maintaining body weight after weight loss (1). However, the effects of protein from different sources were not examined. A study by Claessens et al. (86) investigated the effects of consumption of whey, casein, and carbohydrate on body weight and body composition during weight maintenance after 5 wk of energy restriction. During a 12-wk period, both protein groups showed significantly better weight maintenance after weight loss than the carbohydrate group (Table 3). Proteins induced a greater decrease in body fat mass than carbohydrate, but no difference was found between proteins. In addition, all supplements induced an increase in lean body mass, and they observed a tendency (P = 0.09) for whey to increase lean body mass compared with casein. They thereby support the finding by Cribb et al. (74), who found whey to increase lean body mass to a greater extent than casein during a 10-wk resistance training program. However, they do not agree with the findings by Demling and DeSanti (19) that casein is more beneficial than whey in sparing lean body mass during energy restriction. This may, however, partly be ascribed to the structure of the proteins examined as hydrolyzed casein was studied by Demling and DeSanti (19), whereas intact casein was studied by Claessens et al. (86) and Cribb et al. (74).

Few studies have compared the effects of dairy protein and soy. Baer et al. (43) observed no difference between proteins when looking at body weight, fat mass, and lean body mass. However, they observed that whey was superior to carbohydrate in reducing body weight and fat mass, whereas no difference was observed between soy and carbohydrate. In contrast, Takahira et al. (87) found milk to be superior to soy in reducing body weight and visceral adiposity. In this study, the milk formula contained a larger amount of calcium than the soy formula, and because calcium has shown beneficial effects on body weight (10), part of the effect may also be ascribed to this mineral.

Finally, Hochstenbach-Waelen et al. (52) supported the findings of gelatin on body weight during energy restriction. Both gelatin and milk resulted in a successful weight maintenance period with no weight regain, but no significant differences were observed between proteins (Table 3).

In summary, data provide no clear evidence that whey is better at inducing weight loss or maintaining body weight than casein or vice versa. However, data indicate that protein structure, intact versus hydrolyzed protein, may be of importance, especially when examining the effects of casein because data indicate that the absorption and digestion rates of casein are increased by exogenous hydrolysis. In future studies, as for studies on appetite regulation and energy expenditure, it could therefore be interesting to examine the effects of hydrolyzed casein versus intact casein with regard to changes in body weight and composition.

Conclusion

Despite good evidence to support that protein is beneficial in increasing and maintaining weight loss due to effects on appetite regulation and energy expenditure, data are inconclusive with regard to the effects of various protein types. However, there is some evidence indicating that whey is more satiating than casein in the short term, whereas casein is more satiating in the long term. This may be explained by the differences in protein kinetics between the 2 dairy proteins. When examining the effects on GI hormones, some studies propose whey to be superior to other proteins, especially when studying the effects on GIP, but data are inconsistent, and more studies are needed. Likewise, no consistent data exist on DIT where only very few studies have compared casein and whey. Finally, when interpreting data on appetite and body weight regulation, studies indicate that the structure of the protein seems to be very important, especially when examining the effects of casein.

Based on the studies included in this review, the timing of protein supplementation and measures of appetite and energy expenditure, as well as protein structure, seem to be key elements in the design of future studies. In addition, most studies examining the effects on appetite and energy expenditure only study the acute effects, and in future studies, it would therefore be interesting to study the long-term effects with regard to these parameters.

Acknowledgments

All authors have read and approved the final manuscript.

Footnotes

4

Abbreviations used: αlac, α-lactalbumin; BCAA, branched-chain amino acids; CCK, cholecystokinin; DIT, diet-induced thermogenesis; E%, energy percent; GI, gastrointestinal; GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide 1; GMP, glycomacropeptide; PYY, peptide YY; RQ, respiratory quotient; VAS, visual analogue scale.

Literature Cited

  • 1.Larsen TM, Dalskov SM, van Baak M, Jebb SA, Papadaki A, Pfeiffer AF, Martinez JA, Handjieva-Darlenska T, Kunšová M, Pihlsgård M, et al. Diet, Obesity, and Genes (DIOgenes) Project. Diets with high or low protein content and glycemic index for weight-loss maintenance. N Engl J Med. 2010;363:2102–13 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Skov AR, Toubro S, Ronn B, Holm L, Astrup A. Randomized trial on protein vs carbohydrate in ad libitum fat reduced diet for the treatment of obesity. Int J Obes Relat Metab Disord. 1999;23:528–36 [DOI] [PubMed] [Google Scholar]
  • 3.Weigle DS, Breen PA, Matthys CC, Callahan HS, Meeuws KE, Burden VR, Purnell JQ. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr. 2005;82:41–8 [DOI] [PubMed] [Google Scholar]
  • 4.Mikkelsen PB, Toubro S, Astrup A. Effect of fat-reduced diets on 24-h energy expenditure: comparisons between animal protein, vegetable protein, and carbohydrate. Am J Clin Nutr. 2000;72:1135–41 [DOI] [PubMed] [Google Scholar]
  • 5.Astrup A. The satiating power of protein–a key to obesity prevention? Am J Clin Nutr. 2005;82:1–2 [DOI] [PubMed] [Google Scholar]
  • 6.Gilbert JA, Bendsen NT, Tremblay A, Astrup A. Effect of proteins from different sources on body composition. Nutr Metab Cardiovasc Dis. 2011;21: Suppl 2:B16–31 [DOI] [PubMed] [Google Scholar]
  • 7.Hall WL, Millward DJ, Long SJ, Morgan LM. Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite. Br J Nutr. 2003;89:239–48 [DOI] [PubMed] [Google Scholar]
  • 8.Pal S, Ellis V. The acute effects of four protein meals on insulin, glucose, appetite and energy intake in lean men. Br J Nutr. 2010;104:1241–8 [DOI] [PubMed] [Google Scholar]
  • 9.Acheson KJ, Blondel-Lubrano A, Oguey-Araymon S, Beaumont M, Emady-Azar S, Ammon-Zufferey C, Monnard I, Pinaud S, Nielsen-Moennoz C, Bovetto L. Protein choices targeting thermogenesis and metabolism. Am J Clin Nutr. 2011;93:525–34 [DOI] [PubMed] [Google Scholar]
  • 10.Zemel MB, Thompson W, Milstead A, Morris K, Campbell P. Calcium and dairy acceleration of weight and fat loss during energy restriction in obese adults. Obes Res. 2004;12:582–90 [DOI] [PubMed] [Google Scholar]
  • 11.Faghih S, Abadi AR, Hedayati M, Kimiagar SM. Comparison of the effects of cows’ milk, fortified soy milk, and calcium supplement on weight and fat loss in premenopausal overweight and obese women. Nutr Metab Cardiovasc Dis. 2011;21:499–503 [DOI] [PubMed] [Google Scholar]
  • 12.Abargouei AS, Janghorbani M, Salehi-Marzijarani M, Esmaillzadeh A. Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. Int J Obes (Lond) 2012;36:1485–93. [DOI] [PubMed]
  • 13.Chen M, Pan A, Malik VS, Hu FB. Effects of dairy intake on body weight and fat: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;96:735–47 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Anderson GH, Luhovyy B, Akhavan T, Panahi S. Milk proteins in the regulation of body weight, satiety, food intake and glycemia. Nestle Nutr Workshop Ser Pediatr Program. 2011;67:147–59 [DOI] [PubMed] [Google Scholar]
  • 15.Farrell HM, Jr, Jimenez-Flores R, Bleck GT, Brown EM, Butler JE, Creamer LK, Hicks CL, Hollar CM, Ng-Kwai-Hang KF, Swaisgood HE. Nomenclature of the proteins of cows’ milk–sixth revision. J Dairy Sci. 2004;87:1641–74 [DOI] [PubMed] [Google Scholar]
  • 16.Luhovyy BL, Akhavan T, Anderson GH. Whey proteins in the regulation of food intake and satiety. J Am Coll Nutr. 2007;26:704S–12S [DOI] [PubMed] [Google Scholar]
  • 17.Boirie Y, Dangin M, Gachon P, Vasson MP, Maubois JL, Beaufrere B. Slow and fast dietary proteins differently modulate postprandial protein accretion. Proc Natl Acad Sci U S A. 1997;94:14930–5 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 18.Veldhorst MA, Nieuwenhuizen AG, Hochstenbach-Waelen A, van Vught AJ, Westerterp KR, Engelen MP, Brummer RJ, Deutz NE, Westerterp-Plantenga MS. Dose-dependent satiating effect of whey relative to casein or soy. Physiol Behav. 2009;96:675–82 [DOI] [PubMed] [Google Scholar]
  • 19.Demling RH, DeSanti L. Effect of a hypocaloric diet, increased protein intake and resistance training on lean mass gains and fat mass loss in overweight police officers. Ann Nutr Metab. 2000;44:21–9 [DOI] [PubMed] [Google Scholar]
  • 20.Rolls BJ, Hetherington M, Burley VJ. The specificity of satiety: the influence of foods of different macronutrient content on the development of satiety. Physiol Behav. 1988;43:145–53 [DOI] [PubMed] [Google Scholar]
  • 21.Johnstone AM, Horgan GW, Murison SD, Bremner DM, Lobley GE. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. Am J Clin Nutr. 2008;87:44–55 [DOI] [PubMed] [Google Scholar]
  • 22.Astrup A, Meinert LT, Harper A. Atkins and other low-carbohydrate diets: hoax or an effective tool for weight loss? Lancet. 2004;364:897–9 [DOI] [PubMed] [Google Scholar]
  • 23.Vandewater K, Vickers Z. Higher-protein foods produce greater sensory-specific satiety. Physiol Behav. 1996;59:579–83 [DOI] [PubMed] [Google Scholar]
  • 24.Dove ER, Hodgson JM, Puddey IB, Beilin LJ, Lee YP, Mori TA. Skim milk compared with a fruit drink acutely reduces appetite and energy intake in overweight men and women. Am J Clin Nutr. 2009;90:70–5 [DOI] [PubMed] [Google Scholar]
  • 25.Astbury NM, Stevenson EJ, Morris P, Taylor MA, Macdonald IA. Dose-response effect of a whey protein preload on within-day energy intake in lean subjects. Br J Nutr 2010;104:1858–67. [DOI] [PubMed]
  • 26.Veldhorst MA, Nieuwenhuizen AG, Hochstenbach-Waelen A, Westerterp KR, Engelen MP, Brummer RJ, Deutz NE, Westerterp-Plantenga MS. Comparison of the effects of a high- and normal-casein breakfast on satiety, 'satiety’ hormones, plasma amino acids and subsequent energy intake. Br J Nutr. 2009;101:295–303 [DOI] [PubMed] [Google Scholar]
  • 27.Hochstenbach-Waelen A, Veldhorst MA, Nieuwenhuizen AG, Westerterp-Plantenga MS, Westerterp KR. Comparison of 2 diets with either 25% or 10% of energy as casein on energy expenditure, substrate balance, and appetite profile. Am J Clin Nutr. 2009;89:831–8 [DOI] [PubMed] [Google Scholar]
  • 28.Sousa GT, Lira FS, Rosa JC, de Oliveira EP, Oyama LM, Santos RV, Pimentel GD. Dietary whey protein lessens several risk factors for metabolic diseases: a review. Lipids Health Dis. 2012;11:67. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29.Børsheim E, Tipton KD, Wolf SE, Wolfe RR. Essential amino acids and muscle protein recovery from resistance exercise. Am J Physiol Endocrinol Metab. 2002;283:E648–57 [DOI] [PubMed] [Google Scholar]
  • 30.Burton-Freeman BM. Glycomacropeptide (GMP) is not critical to whey-induced satiety, but may have a unique role in energy intake regulation through cholecystokinin (CCK). Physiol Behav. 2008;93:379–87 [DOI] [PubMed] [Google Scholar]
  • 31.Veldhorst MA, Nieuwenhuizen AG, Hochstenbach-Waelen A, Westerterp KR, Engelen MP, Brummer RJ, Deutz NE, Westerterp-Plantenga MS. Effects of complete whey-protein breakfasts versus whey without GMP-breakfasts on energy intake and satiety. Appetite. 2009;52:388–95 [DOI] [PubMed] [Google Scholar]
  • 32.Keogh JB, Woonton BW, Taylor CM, Janakievski F, Desilva K, Clifton PM. Effect of glycomacropeptide fractions on cholecystokinin and food intake. Br J Nutr. 2010;104:286–90 [DOI] [PubMed] [Google Scholar]
  • 33.Lam SM, Moughan PJ, Awati A, Morton HR. The influence of whey protein and glycomacropeptide on satiety in adult humans. Physiol Behav. 2009;96:162–8 [DOI] [PubMed] [Google Scholar]
  • 34.Veldhorst MA, Nieuwenhuizen AG, Hochstenbach-Waelen A, Westerterp KR, Engelen MP, Brummer RJ, Deutz NE, Westerterp-Plantenga MS. A breakfast with alpha-lactalbumin, gelatin, or gelatin + TRP lowers energy intake at lunch compared with a breakfast with casein, soy, whey, or whey-GMP. Clin Nutr. 2009;28:147–55 [DOI] [PubMed] [Google Scholar]
  • 35.Chatterton D, Smithers G, Roupas P, Brodkorb A. Bioactivity of b-lactoglobulin and a-lactalbumin-Technological implications for processing. Int Dairy J. 2006;16:1229–40 [Google Scholar]
  • 36.Hursel R, van der Zee L, Westerterp-Plantenga MS. Effects of a breakfast yoghurt, with additional total whey protein or caseinomacropeptide-depleted alpha-lactalbumin-enriched whey protein, on diet-induced thermogenesis and appetite suppression. Br J Nutr. 2010;103:775–80 [DOI] [PubMed] [Google Scholar]
  • 37.Heine WE, Klein PD, Reeds PJ. The importance of alpha-lactalbumin in infant nutrition. J Nutr. 1991;121:277–83 [DOI] [PubMed] [Google Scholar]
  • 38.Anderson GH, Tecimer SN, Shah D, Zafar TA. Protein source, quantity, and time of consumption determine the effect of proteins on short-term food intake in young men. J Nutr. 2004;134:3011–5 [DOI] [PubMed] [Google Scholar]
  • 39.Wilson J, Wilson GJ. Contemporary issues in protein requirements and consumption for resistance trained athletes. J Int Soc Sports Nutr. 2006;3:7–27 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 40.Bowen J, Noakes M, Trenerry C, Clifton PM. Energy intake, ghrelin, and cholecystokinin after different carbohydrate and protein preloads in overweight men. J Clin Endocrinol Metab. 2006;91:1477–83 [DOI] [PubMed] [Google Scholar]
  • 41.Bowen J, Noakes M, Clifton PM. Appetite regulatory hormone responses to various dietary proteins differ by body mass index status despite similar reductions in ad libitum energy intake. J Clin Endocrinol Metab. 2006;91:2913–9 [DOI] [PubMed] [Google Scholar]
  • 42.Alfenas RCG, Bressan J, Paiva AC. Effects of protein quality on appetite and energy metabolism in normal weight subjects. Arq Bras Endocrinol Metabol. 2010;54:45–51 [DOI] [PubMed] [Google Scholar]
  • 43.Baer DJ, Stote KS, Paul DR, Harris GK, Rumpler WV, Clevidence BA. Whey protein but not soy protein supplementation alters body weight and composition in free-living overweight and obese adults. J Nutr. 2011;141:1489–94 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 44.Lang V, Bellisle F, Oppert JM, Craplet C, Bornet FR, Slama G, Guy-Grand B. Satiating effect of proteins in healthy subjects: a comparison of egg albumin, casein, gelatin, soy protein, pea protein, and wheat gluten. Am J Clin Nutr. 1998;67:1197–204 [DOI] [PubMed] [Google Scholar]
  • 45.Lang V, Bellisle F, Alamowitch C, Craplet C, Bornet FR, Slama G, Guy-Grand B. Varying the protein source in mixed meal modifies glucose, insulin and glucagon kinetics in healthy men, has weak effects on subjective satiety and fails to affect food intake. Eur J Clin Nutr. 1999;53:959–65 [DOI] [PubMed] [Google Scholar]
  • 46.Lorenzen J, Frederiksen R, Hoppe C, Hvid R, Astrup A. The effect of milk proteins on appetite regulation and diet-induced thermogenesis. Eur J Clin Nutr. 2012;66:622–7 [DOI] [PubMed] [Google Scholar]
  • 47.Potier M, Fromentin G, Calvez J, Benamouzig R, Martin-Rouas C, Pichon L, Tome D, Marsset-Baglieri A. A high-protein, moderate-energy, regular cheesy snack is energetically compensated in human subjects. Br J Nutr. 2009;102:625–31 [DOI] [PubMed] [Google Scholar]
  • 48.Hochstenbach-Waelen A, Westerterp-Plantenga MS, Veldhorst MA, Westerterp KR. Single-protein casein and gelatin diets affect energy expenditure similarly but substrate balance and appetite differently in adults. J Nutr. 2009;139:2285–92 [DOI] [PubMed] [Google Scholar]
  • 49.Gietzen DW, Ross CM, Hao S, Sharp JW. Phosphorylation of eIF2alpha is involved in the signaling of indispensable amino acid deficiency in the anterior piriform cortex of the brain in rats. J Nutr. 2004;134:717–23 [DOI] [PubMed] [Google Scholar]
  • 50.Maurin AC, Jousse C, Averous J, Parry L, Bruhat A, Cherasse Y, Zeng H, Zhang Y, Harding HP, Ron D, et al. The GCN2 kinase biases feeding behavior to maintain amino acid homeostasis in omnivores. Cell Metab. 2005;1:273–7 [DOI] [PubMed] [Google Scholar]
  • 51.Hochstenbach-Waelen A, Soenen S, Westerterp KR, Westerterp-Plantenga MS. Effects of a supra-sustained gelatin-milk protein diet compared with (supra-)sustained milk protein diets on body-weight loss. Br J Nutr. 2011;105:1388–98 [DOI] [PubMed] [Google Scholar]
  • 52.Hochstenbach-Waelen A, Westerterp KR, Soenen S, Westerterp-Plantenga MS. No long-term weight maintenance effects of gelatin in a supra-sustained protein diet. Physiol Behav. 2010;101:237–44 [DOI] [PubMed] [Google Scholar]
  • 53.Nieuwenhuizen AG, Hochstenbach-Waelen A, Veldhorst MA, Westerterp KR, Engelen MP, Brummer RJ, Deutz NE, Westerterp-Plantenga MS. Acute effects of breakfasts containing alpha-lactalbumin, or gelatin with or without added tryptophan, on hunger, 'satiety’ hormones and amino acid profiles. Br J Nutr. 2009;101:1859–66 [DOI] [PubMed] [Google Scholar]
  • 54.Juvonen KR, Karhunen LJ, Vuori E, Lille ME, Karhu T, Jurado-Acosta A, Laaksonen DE, Mykkanen HM, Niskanen LK, Poutanen KS, et al. Structure modification of a milk protein-based model food affects postprandial intestinal peptide release and fullness in healthy young men. Br J Nutr. 2011;106:1890–8 [DOI] [PubMed] [Google Scholar]
  • 55.Dangin M, Boirie Y, Garcia-Rodenas C, Gachon P, Fauquant J, Callier P, Ballevre O. Beaufrere. The digestion rate of protein is an independent regulating factor of postprandial protein retention. Am J Physiol Endocrinol Metab. 2001;280:E340–8 [DOI] [PubMed] [Google Scholar]
  • 56.Dangin M, Guillet C, Garcia-Rodenas C, Gachon P, Bouteloup-Demange C, Reiffers-Magnani K, Fauquant J, Bellèvre O. Beaufrère B. The rate of protein digestion affects protein gain differently during aging in humans. J Physiol. 2003;549:635–44 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 57.Koopman R, Crombach N, Gijsen AP, Walrand S, Fauquant J, Kies AK, Lemosquet S, Saris WH, Boirie Y, van Loon LJ. Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein. Am J Clin Nutr. 2009;90:106–15 [DOI] [PubMed] [Google Scholar]
  • 58.Calbet JA, Holst JJ. Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrolysates in humans. Eur J Nutr. 2004;43:127–39 [DOI] [PubMed] [Google Scholar]
  • 59.Morifuji M, Ishizaka M, Baba S, Fukuda K, Matsumoto H, Koga J, Kanegae M, Higuchi M. Comparison of different sources and degrees of hydrolysis of dietary protein: effect on plasma amino acids, dipeptides, and insulin responses in human subjects. J Agric Food Chem. 2010;58:8788–97 [DOI] [PubMed] [Google Scholar]
  • 60.Akhavan T, Luhovyy BL, Brown PH, Cho CE, Anderson GH. Effect of premeal consumption of whey protein and its hydrolysate on food intake and postmeal glycemia and insulin responses in young adults. Am J Clin Nutr. 2010;91:966–75 [DOI] [PubMed] [Google Scholar]
  • 61.Mahé S, Roos N, Benamouzig R, Davin L, Luengo C, Gagnon L, Gausserges N, Rautureau J, Tome D. Gastrojejunal kinetics and the digestion of [15N]beta-lactoglobulin and casein in humans: the influence of the nature and quantity of the protein. Am J Clin Nutr. 1996;63:546–52 [DOI] [PubMed] [Google Scholar]
  • 62.Sam AH, Troke RC, Tan TM, Bewick GA. The role of the gut/brain axis in modulating food intake. Neuropharmacology. 2012;63:46–56. [DOI] [PubMed]
  • 63.Nilsson M, Stenberg M, Frid AH, Holst JJ, Bjorck IM. Glycemia and insulinemia in healthy subjects after lactoseequivalent meals of milk and other food proteins: the role of plasma amino acids and incretins. Am J Clin Nutr. 2004;80:1246–53 [DOI] [PubMed] [Google Scholar]
  • 64.Nilsson M, Holst JJ, Bjorck IME. Metabolic effects of amino acid mixtures and whey protein in healthy subjects: studies using glucose-equivalent drinks. Am J Clin Nutr. 2007;85:996–1004 [DOI] [PubMed] [Google Scholar]
  • 65.Holmer-Jensen J, Hartvigsen ML, Mortensen LS, Astrup A, de Vrese M, Holst JJ, Thomsen C, Hermansen K. Acute differential effects of milk-derived dietary proteins on postprandial lipaemia in obese non-diabetic subjects. Eur J Clin Nutr. 2012;66:32–8 [DOI] [PubMed] [Google Scholar]
  • 66.Mortensen K, Christensen LL, Holst JJ, Orskov C. GLP-1 and GIP are colocalized in a subset of endocrine cells in the small intestine. Regul Pept. 2003;114:189–96 [DOI] [PubMed] [Google Scholar]
  • 67.Diepvens K, Häberer D, Westerterp-Plantenga M. Different proteins and biopeptides differently affect satiety and anorexigenic/orexigenic hormones in healthy humans. Int J Obes (Lond). 2008;32:510–8 [DOI] [PubMed] [Google Scholar]
  • 68.Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004;23:373–85 [DOI] [PubMed] [Google Scholar]
  • 69.Westerterp KR, Wilson SA, Rolland V. Diet induced thermogenesis measured over 24h in a respiration chamber: effect of diet composition. International journal of obesity and related metabolic disorders. Int J Obes Relat Metab Disord. 1999;23:287–292 [DOI] [PubMed] [Google Scholar]
  • 70.Robinson SM, Jaccard C, Persaud C, Jackson AA, Jequier E, Schutz Y. Protein turnover and thermogenesis in response to high-protein and high-carbohydrate feeding in men. Am J Clin Nutr. 1990;52:72–80 [DOI] [PubMed] [Google Scholar]
  • 71.Karst H, Steiniger J, Noack R, Steglich HD. Diet-induced thermogenesis in man: thermic effects of single proteins, carbohydrates and fats depending on their energy amount. Ann Nutr Metab. 1984;28:245–52 [DOI] [PubMed] [Google Scholar]
  • 72.Fouillet H, Juillet B, Gaudichon C, Mariotti F, Tome D, Bos C. Absorption kinetics are a key factor regulating postprandial protein metabolism in response to qualitative and quantitative variations in protein intake. Am J Physiol Regul Integr Comp Physiol. 2009;297:R1691–705 [DOI] [PubMed] [Google Scholar]
  • 73.Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression 1. Am J Clin Nutr. 2006;83:260–74 [DOI] [PubMed] [Google Scholar]
  • 74.Cribb PJ, Williams AD, Carey MF, Hayes A. The effect of whey isolate and resistance training on strength, body composition, and plasma glutamine. Int J Sport Nutr Exerc Metab. 2006;16:494–509 [DOI] [PubMed] [Google Scholar]
  • 75.Colker CM, Swain MA, Fabrucini B, Shi Q, Kaiman DS. Effects of supplemental protein on body composition and muscular strength in healthy athletic male adults. Curr Ther Res. 2000;61:19–28.
  • 76.Kerksick CM, Rasmussen CJ, Lancaster SL, Magu B, Smith P, Melton C, Greenwood M, Almada AL, Earnest CP, Kreider RB. The effects of protein and amino acid supplementation on performance and training adaptations during ten weeks of resistance training. J Strength Cond Res. 2006;20:643–53 [PubMed] [Google Scholar]
  • 77.Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009;107:987–992 [DOI] [PubMed] [Google Scholar]
  • 78.Lollo PCB, Amaya-Farfan J, de Carvalho-Silva LB. Physiological and physical effects of different milk protein supplements in elite soccer players. J Hum Kinet. 2011;30:49–57 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 79.Frestedt JL, Zenk JL, Kuskowski MA, Ward LS, Bastian ED. A whey-protein supplement increases fat loss and spares lean muscle in obese subjects: a randomized human clinical study. Nutr Metab (Lond). 2008;5:8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 80.Anderson JW, Hoie LH. Weight loss and lipid changes with low-energy diets: comparator study of milk-based versus soy-based liquid meal replacement interventions. J Am Coll Nutr. 2005;24:210–6 [DOI] [PubMed] [Google Scholar]
  • 81.Anderson JW, Fuller J, Patterson K, Blair R, Tabor A. Soy compared to casein meal replacement shakes with energy-restricted diets for obese women: randomized controlled trial. Metabolism. 2007;56:280–8 [DOI] [PubMed] [Google Scholar]
  • 82.Soenen S, Hochstenbach-Waelen A, Westerterp-Plantenga MS. Efficacy of alpha-lactalbumin and milk protein on weight loss and body composition during energy restriction. Obesity (Silver Spring). 2011;19:370–9 [DOI] [PubMed] [Google Scholar]
  • 83.Pilvi TK, Harala S, Korpela R, Mervaala EM. Effects of high-calcium diets with different whey proteins on weight loss and weight regain in high-fat-fed C57BL/6J mice. Br J Nutr. 2009;102:337–41 [DOI] [PubMed] [Google Scholar]
  • 84.Keogh JB, Clifton P. The effect of meal replacements high in glycomacropeptide on weight loss and markers of cardiovascular disease risk. Am J Clin Nutr. 2008;87:1602–5 [DOI] [PubMed] [Google Scholar]
  • 85.Royle PJ, McIntosh GH, Clifton PM. Whey protein isolate and glycomacropeptide decrease weight gain and alter body composition in male Wistar rats. Br J Nutr. 2008;100:88–93 [DOI] [PubMed] [Google Scholar]
  • 86.Claessens M, van Baak MA, Monsheimer S, Saris WH. The effect of a low-fat, high-protein or high-carbohydrate ad libitum diet on weight loss maintenance and metabolic risk factors. Int J Obes (Lond). 2009;33:296–304 [DOI] [PubMed] [Google Scholar]
  • 87.Takahira M, Noda K, Fukushima M, Zhang B, Mitsutake R, Uehara Y, Ogawa M, Kakuma T, Saku K. Randomized, double-blind, controlled, comparative trial of formula food containing soy protein vs. milk protein in visceral fat obesity. -FLAVO study-. Circ J. 2011;75:2235–43 [DOI] [PubMed] [Google Scholar]
  • 88.Hermansen K, Hansen B, Jacobsen R, Clausen P, Dalgaard M, Dinesen B, Holst JJ, Pedersen E, Astrup A. Effects of soy supplementation on blood lipids and arterial function in hypercholesterolaemic subjects. Eur J Clin Nutr. 2005;59:843–50 [DOI] [PubMed] [Google Scholar]

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