recent studies in animals and humans have shown that whey proteins have anorexigenic properties that may be a potential weapon for overweight management . in particular , the anorectic effect of whey proteins ( wp ) is stronger than that induced by casein , soy proteins and ovalbumin . casein macropeptide ( cmp ) , which is the precursor protein of glyco macropeptide ( gmp ) , is a bioproduct of rennin ( chymosin ) and a component of whey ( 1.21.5 20  years ago , it was shown that gmp can affect gastrointestinal function through the inhibition of gastric secretion , and that this action could be mediated by peptide hormones , such as cholecystokinin ( cck ) [ 3 , 4 ] , which is a potent activator of satiety signals . the cck - like activity of gmp was then confirmed by subsequent studies [ 5 , 6 ] . its satiating power and weight control action are extremely variable and depend on the physical and chemical properties determining its digestion and absorption with the subsequent release of amino acids . circulating postprandial amino - acid ( aa ) levels are amongst the main factors that influence satiety . there is a wealth of evidence that whey protein effect on satiety and food intake is mediated by the release of satiety - inducing hormones . many of them are involved in regulating food intake and are sensitive to content and composition of intestinal nutrients . a number of them respond after protein consumption and this may account for food intake suppression after milk protein ingestion . cck , glp-1(glucagon - like peptide-1 ) , gip ( gastric inhibitory polypeptide ) , pyy ( peptide yy ) , and ghrelin in particular , play a key role . insulin is involved in the regulation of food intake , both in the short and the long term . insulin release is stimulated by whey protein ingestion that affects the glycemic response and is closely associated with short - term satiety and decreased food intake . insulin response has been shown to have a closer correlation with short - term satiety and food intake than do gut hormones . anyways , the satiating effects of wp have been proven only when they are administered in a single - dose high load ( 2040  g ) . this could lead to an protein overload if we consider the recommended dietary allowance ( rda ) when the rest of daily food intake is concerned . therefore , it could be very interesting to evaluate whether wp lower dosage also determines a similar satiating effect . the aim of this study was to evaluate the satiety - inducing effect and the effect on satiety - associated gut hormones ( cck , glp-1 , pyy 136 ) of an oral administration of low - load whey proteins versus casein ( 8  g / dose ) . a double - blind crossover study has been conducted employing five healthy volunteer subjects [ bmi ( body mass index ) between 22 and 26  kg / mq , aged 2555  years ] . in acute , five samples were performed for the first and the second arm of the study with 1-week washout between the two doses . patients excluded from the study were those with the following contraindications : eating disorders , particularly binge eating disorder ( bed ) , bulimia;known or suspected pregnancy;depression and/or obsessive  compulsive disorder treated with serotoninergic drugs;intake of appetite suppressor drugs;inhibiting pancreatic lipase;renal failure . eating disorders , particularly binge eating disorder ( bed ) , bulimia ; known or suspected pregnancy ; depression and/or obsessive  compulsive disorder treated with serotoninergic drugs ; intake of appetite suppressor drugs ; inhibiting pancreatic lipase ; after informed consent has been obtained , each subject underwent the following baseline evaluations : anamnesis and physical examination;anthropometric measures : body weight with calculation of bmi and waist circumference , andassessment of average daily calorie intake by food diary anamnesis and physical examination ; anthropometric measures : body weight with calculation of bmi and waist circumference , and assessment of average daily calorie intake by food diary the study was conducted after an overnight fast and the samples were carried out as follows : the satiating capacity was evaluated by means of haber s scale , an analog visual scale from 10 ( representing extreme hunger : painfully hungry ) to + 10 ( representing extreme satiety : full to nausea ) . in particular , the subjects describe the level of agreement with respect to hunger or satiety by pointing to an appropriate place along the graduated visual scale . assessment of tolerability ( adverse events monitoring and reference ) , which has been transformed in a scale from 1 to 20 for an easy report.detection of side effects.five samples were made for each study arm ( t0 : 0 ; t1 : 15 ; t2 : 30 ; t3 : 90 ; t4 : 180).cck , glp-1 and pyy were assayed in duplicate using radioimmunoassay ( ria kit the satiating capacity was evaluated by means of haber s scale , an analog visual scale from 10 ( representing extreme hunger : painfully hungry ) to + 10 ( representing extreme satiety : full to nausea ) . in particular , the subjects describe the level of agreement with respect to hunger or satiety by pointing to an appropriate place along the graduated visual scale . assessment of tolerability ( adverse events monitoring and reference ) , which has been transformed in a scale from 1 to 20 for an easy report . five samples were made for each study arm ( t0 : 0 ; t1 : 15 ; t2 : 30 ; t3 : 90 ; t4 : 180 ) . the procedure contemplates : plasma collection the blood was collected into tubes containing edta ( greiner vacuette k3e k3edta , 4  ml , lavender / black , 13    75  mm ) , ridged and stirred gently to prevent coagulation . then it was transferred into tubes containing aprotinin ( 0.6  tiu / ml of blood ) , stirred gently several times to inhibit the activity of proteinase and centrifuged at 1,600g for 15  min at 4  c . plasma extraction the plasma was acidified and centrifuged at 10,000g for 20  min at 4  c then it was loaded onto columns containing 200  mg of sep column c18 , equilibrated with buffer b ( buffer b : 60  % acetonitrile in 1  % tfa ) and a [ buffer a : 1  % trifluoroacetic ( tfa ) ] . the eluate was collected in tubes of polystyrene , concentrated , lyophilized and then reconstituted with ria buffer . the composition of the product ( containing whey proteins ) ( colordiet , inpha duemila s.r.l . , via elettrochimica n.37 , lecco , italy ) was : proteins of the whey concentrate 80  % 10,000.0  mgstarchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mgglucomannan 1,000.0  mgexcipients , sweeteners , flavoring or similar tropical proteins of the whey concentrate 80  % 10,000.0  mg starchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mg glucomannan 1,000.0  mg excipients , sweeteners , flavoring or similar tropical the composition of the product ( containing casein ) was : casein of milk concentrated 80  % 10,000.0  mgstarchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mgglucomannan 1,000.0  mgexcipients , sweeteners , flavoring or similar tropical casein of milk concentrated 80  % 10,000.0  mg starchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mg glucomannan 1,000.0  mg excipients , sweeteners , flavoring or similar tropical five healthy subjects were enrolled in this crossover study . all data were tabulated and subjected to appropriate statistical analysis by the biostatistics spss package . effectiveness and tolerability regarding the subjects who completed the study ( drop - outs were replaced ) were measured . student s t tests were used for parametric data and the wilcoxon s test was relied on for non - parametric tests . the non - parametric friedman test was applied to evaluate the differences in satiation feeling ( haber s score ) . if significant differences were identified , all the possible pairwise comparisons were investigated with non - parametric wilcoxon s test for paired data , adjusting the reference , the p value ( 0.05 ) , according to bonferroni s method . the efficacy on the feeling of satiety was assessed by the net change from the baseline at the end of follow - up . unpaired t test ( with satterthwaite s correction for degrees of freedom ) or the analogous non - parametric wilcoxon  mann whitney s test ( mw ) was applied . a value of p  <  0.05 was considered significant ( two - side ) . the composition of the product ( containing whey proteins ) ( colordiet , inpha duemila s.r.l . , via elettrochimica n.37 , lecco , italy ) was : proteins of the whey concentrate 80  % 10,000.0  mgstarchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mgglucomannan 1,000.0  mgexcipients , sweeteners , flavoring or similar tropical proteins of the whey concentrate 80  % 10,000.0  mg starchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mg glucomannan 1,000.0  mg excipients , sweeteners , flavoring or similar tropical the composition of the product ( containing casein ) was : casein of milk concentrated 80  % 10,000.0  mgstarchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mgglucomannan 1,000.0  mgexcipients , sweeteners , flavoring or similar tropical casein of milk concentrated 80  % 10,000.0  mg starchlite white bean seeds e.g. aaiu 3,000 ( 3,000 alpha amylase inhibiting unit ) 500.0  mg glucomannan 1,000.0  mg excipients , sweeteners , flavoring or similar tropical all data were tabulated and subjected to appropriate statistical analysis by the biostatistics spss package . effectiveness and tolerability regarding the subjects who completed the study ( drop - outs were replaced ) were measured . student s t tests were used for parametric data and the wilcoxon s test was relied on for non - parametric tests . the non - parametric friedman test was applied to evaluate the differences in satiation feeling ( haber s score ) . if significant differences were identified , all the possible pairwise comparisons were investigated with non - parametric wilcoxon s test for paired data , adjusting the reference , the p value ( 0.05 ) , according to bonferroni s method . the efficacy on the feeling of satiety was assessed by the net change from the baseline at the end of follow - up . unpaired t test ( with satterthwaite s correction for degrees of freedom ) or the analogous non - parametric wilcoxon  mann whitney s test ( mw ) was applied . a value of p  <  0.05 was considered significant ( two - side ) . analysis of the data showed that the wp administration induced a significant decrease in appetite after 90  min ( p  <  0.05 ) compared to casein ( table  1).table  1appetite and enterohormonal profile following whey proteinstime ( min.)0153090180appetite15.0    4.312.6    4.312.6    4.212.2    4.0 * 13.2    4.8glp-1 pmol / l6.16    1.786.80    1.616.94    1.77.11    1.08**6.77 2.09cck ng / ml1.1    0.11.17    0.181.17    0.171.3    0.251.16    0.16pyy pg / ml19.7    0.319.4    0.519.6    0.319.7    0.519.7    0.4 
 cck ns , pyy ns *  appetite : t0 vs. t90 p  =  0.0446 * *  glp-1 : t0 vs. t90 p  =  0.0166 appetite and enterohormonal profile following whey proteins *  appetite : t0 vs. t90 p  =  0.0446 * *  glp-1 : t0 vs. t90 p  =  0.0166 plasma gut hormone concentration increased significantly only for glp-1 ( p  <  0.05 ) after 90  min in wp group , while after 180  min ( p  <  0.05 ) in the casein group ( tables  1 , 2 ) . there is a significant correlation between glp-1 and decrease in appetite in wp ( r  =  0.93 ) . cck concentration tends to increase after 90  min even though it does not attain statistical significance ( p  =  0.091).table  2appetite and enterohormonal profile following caseintime ( min.)0153090180appetite11.4    7.89.6    6.47.7    4.79.4    5.511.8    6.8glp-17.0    1.1 * 7.1    1.26.74    1.17.2    1.27.2    1.2*cck1.4    0.11.3 pg / ml19.7    0.319.5    0.319.7    0.419.8    0.519.9    0.6 
 appetite ns , cck ns , pyy ns *  glp-1 : t0 vs. t180 p  =  0.0129 appetite and enterohormonal profile following casein 
 appetite ns , cck ns , pyy ns *  glp-1 : t0 vs. t180 p  =  0.0129 since , glucomannan can not affect gut hormone response [ 913 ] and similarly , phaseolamin does not affect gut hormone - mediated appetite modulation because it blocks amylase in the digestion of complex carbohydrates ( starch ) , the discussion will focus on the different protein compositions of the supplement [ 1417 ] . it is well known that , compared to a standard diet , a high - protein diet increases satiety , postprandial thermogenesis ( by decreasing energy efficiency in futile cycles ) , basal metabolism , protein balance , and fat oxidation . in addition , high biological value proteins have a greater effect on energy expenditure than the others . finally , a protein - rich diet seems to have a positive effect on bone mineralization and to cause a reduction of fractures due to osteoporosis . physiologically , a high - protein diet produces a prolonged feeling of satiety by stimulating the secretion of anorectic hormones . despite these interesting premises , a highly hyper protein diet ( > 2  g / kg / day ) can cause nitrogen overload on the kidney due to sulfur amino acids , therefore , caution should be taken in considering this approach in patients with or at risk of renal disease and those with metabolic syndrome , . this is why in recent years , more attention has been focused on evaluating the anorectic components of proteins to check the difference in their compositions so that they may be used in a more rational and modular manner . noted that in a diet where 10  % of energy was provided by proteins , wp showed a greater satiating effect than caseins and soy proteins . when dietary protein provided 25  % of energy , differences in satiety induced by the three different types of proteins were no longer observed , although the wp induced a greater hormonal stimulation . the authors concluded that the differences observed were the result of the different amounts of amino acids , some of which were present in greater concentrations , beyond the threshold for activation of anorectic gut hormone secretion . recent studies in animals and humans have shown that wp have anorexigenic properties that may be a potential weapon for overweight management [ 2023 ] . in particular , studies by sukkar and others [ 21 , 22 ] have shown that wps are able to reduce food intake and consequently gain weight both in wistar and in obesity - prone zucker rats . cmp , which is the precursor protein of gmp , a bioproduct of rennin ( chymosin ) and a component of whey ( 1.21.5 g / l ) may have anorectic activity . over 20  years ago , it was shown that gmp can affect gastrointestinal function through the inhibition of gastric secretion , and that this action could be mediated by peptide hormones , such as cck [ 25 , 26 ] , a potent activator of satiety signals . the cck - like activity of gmp was confirmed by subsequent studies [ 27 , 28 ] . confirmed that , being a wp fraction , gmp reduces energy intake because of its greater content in amino acids : serine , threonine , alanine , isoleucine , and -aminobutyric acid , regardless of the remaining wp components . whey proteins were found to determine a maximum satiety response in that once a certain anorectic hormone concentration is reached , the effect on satiety plateaus irrespective of the progressive increase in anorectic hormones due to additional whey protein intake . the control of satiety by wp is also determined by a second mechanism related to their physical and chemical properties . these properties bring about different digestion and absorption modalities resulting in differing degrees of amino - acid release , with circulating postprandial aa levels acting as one of the main factors that influence satiety . fast  or  slow  depending on their different digestion and absorption times and on their contribution to protein synthesis and postprandial plasma aa concentrations . after ingestion , wp rapidly pass through the stomach and reach the jejunum as intact proteins . by contrast , casein undergoes substantial digestion in the stomach due to the strongly acid environment and coagulates forming lumps , passing more slowly through the small intestine . in the small intestine , whey protein is hydrolyzed more slowly than the other proteins , and digested and absorbed within a wider tract . based on the plasma amino - acid concentrations observed after an oral load , whey digestion and absorption of its amino acids similarly , mice and rats fed with whey reduce their food intake 30  min after administration than when fed with casein [ 21 , 32 ] . . the protein efficiency ratio ( per ) , which reflects the weight gain in laboratory animals per gram of protein taken after 4  weeks , is very high ( 3.2 ) and greater than casein ( 2.6).this feature may be one of the factors that determine their satiating power since , compared to other proteins , whey proteins contain a higher concentration of branched - chain amino acids , especially l - leucine . leucine acts on an mtor - dependent kinase that is non - insulin dependent , promotes anabolism of muscle tissue , maintains stable glucose levels , and lowers insulin during energy restriction . leucine crosses the blood  brain barrier more rapidly than other amino acids , and its important role in hypothalamic regulation of food intake has been demonstrated in the recent studies . direct intracerebroventricular injection of amino - acid mixtures ( rpmi 1640 ) and leucine alone ( 1  g ) inhibits food intake for 24  h , indicating that an increase in brain amino - acid concentrations is sufficient to suppress food intake . this effect is related to increased mrna agrp ( agouti - related protein ) levels in hypothalamic gt1 - 7 cells exposed to low - amino - acid concentrations for 16  h , and is attenuated when leucine is removed from the cell culture . it may be mediated by metabolic - sensing neurons [ 38 , 39 ] via an mtor - dependent mechanism , in which an increase in the brain amino - acid concentration leads to appetite inhibition . increasing evidence has shown that the effect of whey proteins on satiety and food intake is mediated by the effect of satiety - inducing hormone release [ 7 , 42 ] . cholecystokinin is known as a satiety hormone , in rats , cck and its receptor subtype a are involved in the suppression of food intake induced by proteins [ 43 , 44 ] . in humans , proteins and fats in the diet are the main stimulators of cck secretion , and digestion of proteins is necessary for the release of cck . milk proteins increase cck plasma concentration , with an initial peak after 1520  min , following , which there is a fall and a subsequent increase after about 90  min [ 23 , 47 ] . whey increased cck concentration to a greater extent than did casein in a study by hall   but not in one by bowen . this could be due to differences in the gmp content of the wheys used in the investigations . glucagon - like peptide-1 also appears to play a role in protein - induced satiety . both carbohydrates and fats are potent stimulators of glp-1 , but milk proteins stimulate the release of glp-1 regardless of the presence or absence of carbohydrates and fats . whey appears to have a more potent action and its secretagogue effect can be increased in the presence of other micronutrients . a high - protein breakfast ( 58  % of total energy ) , consisting mainly of whey protein - enriched dietetic products , increases glp-1 concentrations after 3  h compared to a high - carbohydrate breakfast with yoghurt ( mainly casein ) . in human studies , a whey protein load ( 50  g ) administered with 200  kcal from fats and carbohydrates caused greater glp-1 plasma concentrations than casein , again after 3  h . evidence of the indirect role of glp-1 on milk protein - induced satiety was provided by studies on rats showing that exendin-4 ( ex-4 ) , a glp-1 receptor agonist , interacts with milk proteins in suppressing food intake [ 50 , 51 ] . this effect was observed both when the proteins were administered intact , partially hydrolyzed or in the form of free amino acids . the glucose - dependent insulinotropic polypeptide , gip , is released by k cells in the duodenum after food intake , and may have an important role in the development of obesity , since gip receptor knockout mice were observed to be resistant to obesity even if fed a high - fat diet . recent studies have shown that a whey - containing beverage significantly increased gip response ( to 80  % ) in healthy subjects , while mixtures of branched - chain amino acids did not have the same effect . it is possible that bioactive peptides present in whey or formed during digestion are the main stimulators of gip secretion . branched - chain amino - acid mixtures do not stimulate gut hormone ( gip and glp-1 ) response , whereas whey protein drinks produce an increased response , suggesting that the action of whey proteins is not simply related to the amino - acid content but it is also due to the action of peptics . the peptide yy is a gut hormone secreted by intestinal l cells and is present throughout the intestinal tract , with a higher concentration in the distal ileum . pyy plasma concentration increases after the intragastric administration of whey proteins or whey peptides hydrolysates in healthy subjects , and it is not related to the degree of protein fractionation . no comparisons between the effect of whey and that of other proteins have been reported . ghrelin is a digestive orexigenic hormone   released into the circulation by the stomach ; its concentrations generally reach a peak before meals , while its action is suppressed by food intake . like other digestive hormones , all three classes of macronutrients can suppress plasma ghrelin , but with different levels of efficiency . loads of milk protein , casein , whey or gmp in rats all produced a similar reduction of ghrelin plasma concentrations after 30  min compared to placebo ( water alone ) . in humans , whey proteins and calcium caseinate suppress ghrelin concentrations similarly to lactose and more than glucose after 3  h. this effect was correlated with a further reduction in subsequent energy intake . milk proteins and particularly the whey protein fraction have bioactive properties ( hormones , growth factors , cytokines , antioxidants and stimulation of protein synthesis ) , which determine physiological regulations . whey proteins also have an antioxidant effect that could be useful in controlling the oxidative stress occurring in the metabolic syndrome . they increase glutathione ( gsh ) synthesis and have been shown to boost immunity by increasing lymphocyte and splenic gsh synthesis [ 21 , 5564 ] . recently , pall et al .   have shown that total and ldl cholesterol reduced significantly after a 12-week treatment with whey proteins versus casein , in 70 obese human subjects ( bmi  =  1.3    0.8  kg / m ) in sum , analysis of the findings reported revealed that a whey protein load induced a significant decrease in eating desire after 90  min ( p  <  0.05 ) , compared to casein . as for the gut hormone plasma concentrations , only glp-1 increased significantly ( p  <  0.05 ) 90  min after whey protein administration and 180  min after casein administration ( p  <  0.05 ) and there was a significant correlation between glp-1 and decreased eating desire ( r  =  0.93 ) . cck concentrations also tended to increase after 90  min , but this is not statistically significant ( p  =  0.091 ) for whey proteins . these results may be due to : the small number of cases studiedthe small amount of proteins used . in fact , other experiments have actually shown a significant increase in cck and pyy after administration of 2058  g of whey proteins . with regard to pyy , the findings reported are not consistent with the data described in the literature for the same reasons itemized for cck . given the small amount of whey proteins used , the proteins may not have reached the site where there is a greater pyy secretion as they are absorbed in the duodenum and jejunum , while the pyy - secreting cells are mainly localized in the distal ileum . in conclusion , this study suggests that a mixture of whey proteins and glucomannan reduces eating desire and that this effect is related both to the changes in gut hormone levels ( glp-1 ) despite the low protein content ( 10  g ) , and to the presence of glucomannan that forms a  net  after gelling in the acid milieu of the stomach . it is interesting to note that the result was achieved despite the low protein content ( 10  g ) , which is compatible with a clinical use of product . elsewhere in the literature mixtures containing , we suggest that dietary supplementation with whey proteins might be employed as a treatment for appetite control . whey proteins present the added value of being a source of branched - chain amino acids and leucine that are particularly appropriated for lean body mass maintenance in the course of low - calorie diets . future studies on larger populations are called for further investigations to analyze the effects both on appetite and hormones ( cck , glp-1 , pyy 136 ) , and varying the amounts of whey proteins versus caseins .
whey proteins represent the most satiating nutrients . in particular , their effects are due to enterohormonal changes ( cck , glp-1 and pyy 136 ) observed after their exclusive ingestion . 
 glucomannan has important satiety property due to volume increase following gelification . 
 the aim of the study is the evaluation of subjective rate of hunger and enterohormone concentrations ( cck , glp-1 , pyy 136 ) following oral loading of a mixture containing wp ( 8  g ) or casein ( 8  g ) plus glucomannan ( 1  g ) ( colordiet , inpha duemila srl lecco , italy ) . 
 the study was conducted as a double - blind crossover with five healthy volunteers ( bmi 2226  kg / m2 aging 1865  years ) in acute and a wash - out period of 1  week between the first and the second evaluation . from the analysis of the data , we observe that the load with wp induces a significant decrease in the desire to eat after 90  min ( p  <  0.0446 ) when compared with casein . as far as plasma hormones are concerned , there was a significant increase only in glp-1 at 90  min after wp ( p  <  0.00166 ) and 180  min after casein ( t0 vs. t180 p  =  0.000129 ) . 
 there is a significant correlation between the increase in glp-1 and decrease of desire to eat ( r  =  0.93 ) . 
 there is a tendency to the increasing of cck after 90  min , which is not significant ( p  =  0.091 ) . 
 these results could be due to ( a ) the low number of cases or ( b ) the low dose of protein used . 
 the present study suggests that a mixture of wp plus glucomannan exerts a decrease in the desire to eat which is correlated to enterohormonal modification ( glp-1 increase ) despite the low content of protein ( 8  g ) and the presence of glucomannan , which could reduce the fast absorption of wp in relation to the net forming during the gelification of the gastric environment .