[Truncated abstract] Obesity is now a major public health problem worldwide. More than half the Australian population is now overweight. This is an important public health concern primarily because of the impact of overweight and obesity on risk of diabetes, hypertension and cardiovascular disease. Many strategies have been proposed to fight the obesity epidemic. One possible strategy involves understanding of the role of dietary components in the control of food intake. In this regard, dietary protein and fibre appear to be the most satiating nutrients. Foods enriched in protein, replacing energy from carbohydrate, or dietary fibre can increase satiety and reduce energy intake in the short-term. Longer-term trials suggest benefits of increasing protein or fibre intake on weight loss and features of the metabolic syndrome. The effects of dietary approaches which increase both protein and fibre at the expense of refined carbohydrate are uncertain. A practical approach to increasing both protein and fibre content of processed foods is to incorporate high protein and fibre ingredients into high carbohydrate foods. Lupin kernel flour is a novel food ingredient derived from the endosperm of lupin. It contains 40 to 45% protein, 25 to 30% fibre, and negligible sugar and starch. Lupin kernel flour can be incorporated into refined carbohydrate rich foods such as bread to increase protein and fibre content at the expense of refined carbohydrate. ... Body weight was measured every 2 weeks throughout the 16 week intervention, and these data were analysed to determine whether there was any between group difference in the rate of change in weight over 16 weeks. Over 16 weeks, lupin bread compared to white bread resulted in a significant increase in protein (13.7 (2.3, 25.0) g/d) and fibre (12.5 (8.8, 16.2) g/d) intakes, and a decrease in carbohydrate intake (-19.9 (-45.2, 5.5) g/d). There was a significant difference between groups in the rate of weight change over the 16 weeks (P=0.05). However, at 16 weeks there was no significant effect on body weight (-0.4 (-1.3, 0.6) kg), fat mass (-0.5 (-1.2, 0.2) kg) or fat free mass (0.2 (-0.5, 0.8) kg). Plasma adiponectin and leptin were not altered. Mean 24 hour systolic blood pressure (-2.4 (-3.4, -1.3) mm Hg) and pulse pressure (-3.1 (-3.9, -2.3) mm Hg) were lower for lupin relative to white bread, but diastolic blood pressure was not significantly different between groups. Apart from a lower HDL cholesterol for lupin relative to white bread (-0.09 (-0.17, -0.01) mmol/L), there were no significant differences in other blood lipids and glucose and insulin concentrations. Interpretation of the results was not influenced after adjustment for potential confounding factors. These studies assessed effects of bread enriched in lupin kernel flour relative to white bread, resulting in a higher protein and fibre intake and lower refined carbohydrate intake. This increased satiety and reduced energy intake acutely, but did not significantly influence body weight over 16 weeks. Systolic blood pressure and pulse pressure were significantly reduced. There were no significant improvements in blood lipids or glucose and insulin concentrations. Therefore, increasing protein and fibre intake at the expense of refined carbohydrate using lupin kernel flour may benefit satiety and blood pressure. Longer-term trials incorporating weight loss may be needed to observe benefits on body weight.

Obesity is pandemic. Pharmacological treatment development depends on modeling the regulation of feeding, particularly by free fatty acids (FFA). Most models have been employed in the rat in vivo, and show FFA-stimulated intestinal satiety signals are dependent on the fat’s acyl chain-length, involve cholecystokinin (CCK) secretion, and are mediated by vagal afferents. I hypothesized that an in vitro mouse model could be employed, with sensitivity to measure afferent responses to nutrient stimuli. Male C57BL/6N mice were killed, the intestine harvested en bloc, and a jejunal section dissected with neurovascular mesenteric arcade emanating centrally. The tissue was placed in a Krebs-superfused chamber, the lumen cannulated with the outlet open to drain, and Krebs or other mediators were continuously perfused intraluminally. The dissected afferent nerve was placed in a suction electrode for extracellular recording. Afferent responses to distension and the perfusion of mediators (e.g. CCK or FFA) were tested. Preparations from normal mice (no surgery), or from mice following chronic subdiaphragmatic vagotomy or sham operation, were used to assess vagal afferent contributions. Luminally-perfused CCK (100 nM) increased afferent firing. This response was abolished with the CCK-1 receptor antagonist lorglumide (10 µM). The short-chain fatty acid (SCFA) sodium butyrate (30 mM) potentiated firing. The long-chain fatty acid (LCFA) sodium oleate (1-300 mM) activated concentration-dependent firing (EC50=25.35 mM) that was significantly greater at 30 mM than that evoked by butyrate. Lorglumide (30 µM) abolished the oleate (30 mM) response. The L-type Ca2+ channel (LTCC) inhibitor nicardipine (3 µM), intraluminally, potentiated the oleate response, while bath application abolished it. Vagotomy attenuated the oleate response. Vagotomy abolished the intraluminal CCK (100 nM) response, and attenuated the response to bath-superfused CCK. These findings support FFA chain-length-dependent mesenteric afferent activation and CCK involvement in oleate-induced firing, and suggest LTCC mediation of excitatory and inhibitory oleate response transduction pathways. The murine oleate response was shown to be mostly vagally-mediated, with some spinal contribution, and both vagal and spinal contributions to CCK responses were suggested. These data provide a basis for further investigation in vitro of cellular and molecular mechanisms of afferent satiety signals, and ultimately of obesity pathogenesis. / Thesis (Master, Physiology) -- Queen's University, 2010-06-29 15:56:08.387

Climatério é a fase da vida da mulher em que ocorrem alterações hormonais que culminam em alterações metabólicas peculiares desse período, como por exemplo, diminuição do gasto energético e ganho ponderal. Com isso, os objetivos do presente trabalho foram mensurar o gasto energético e calcular a oxidação de carboidratos e lipídios, nos momentos basal e após uma sobrecarga lipídica, de mulheres pós-menopausadas com excesso de peso, estratificadas de acordo com o nível do estradiol plasmático (E2), bem como analisar peptídeos reguladores da fome e da saciedade nos mesmos momentos. Os grupos de mulheres foram: grupo 1- E2 39 pg/mL, 2- 40 E2 59 pg/mL, e 3- E2 60 pg/mL. As voluntárias receberam uma única refeição de 1100 kcal e 72% de lipídios, a qual caracterizou a sobrecarga lipídica. O gasto energético foi medido por calorimetria indireta por um período de cinco horas, sendo que as mensurações foram realizadas nos momentos 30, 60, 90, 150, 210 e 270 minutos. Os peptídeos reguladores da fome e da saciedade foram analisados no momento basal, após 30 e 270 minutos da sobrecarga lipídica. Os grupos foram comparados pelo teste não paramétrico Kruskal-Wallis, e para a comparação entre os momentos no mesmo grupo, foi utilizado o modelo de regressão linear com efeitos mistos, considerando p<0,05(*). Quarenta e quatro mulheres pós-menopausadas foram estudadas, com idade de 55±5 anos (média±desvio padrão), índice de massa corporal de 31±4 kg/m² e tempo de pós-menopausa de 8±7 anos. De uma forma geral, o gasto energético de repouso foi de 1337±194* kcal/dia, aumentando para 1476±295* kcal/dia nos primeiros 30´ pós-prandiais, e para 1513±318* kcal/dia ao final. Entre os grupos, não houve diferença estatística significativa. Em relação à oxidação de carboidratos, o valor basal foi de 151±95 mg/min, diminuindo para 146±95 mg/min nos primeiros 30´, e para 122±44 mg/min ao final (valores convertidos para mg/min para facilitar a leitura). O valor basal da oxidação lipídica foi de 37±30* mg/min, aumentando para 52±24* mg/min nos primeiros 30´ pós-prandiais, e para 63±21* mg/min ao final. Entre os grupos, não houve diferença estatística significativa quanto à oxidação de carboidratos, e quanto aos lipídios, houve diferença apenas entre os grupos 1 (maiores valores, p=0,03) e 2 ao final do experimento , e entre os grupos 1 e 3 (maiores valores, p=0,04) no momento 150´. Quanto aos peptídeos, o valor basal da leptina foi de 47±29 ng/mL, diminuindo para 44±27 ng/mL nos primeiros 30´ pós-prandiais, e para 43±26 ng/mL ao final. O valor basal da grelina foi de 753±522 pg/mL, diminuindo para 705±420 pg/mL nos primeiros 30´, e para 561±343 pg/mL ao final. O valor basal do peptídeo YY foi de 92±40* pg/mL, aumentando para 153±63* pg/mL nos primeiros 30´, e para 214±66* pg/mL ao final. Quanto à colecistocinina, o valor aos 30´ foi de 1,8±2,3 pg/mL, aumentando para 2,2±1,7 pg/mL ao final. Entre os grupos, houve diferença estatística significativa apenas da colecistocinina entre os grupos 2 e 3 (maiores valores, p=0,04) ao final. Sendo assim, houve um aumento significativo e gradual do gasto energético após a sobrecarga lipídica; predomínio da oxidação de carboidratos em relação à de lipídios, havendo uma diminuição em sua oxidação e um aumento da oxidação lipídica após a sobrecarga. Quanto aos grupos, não houve diferença estatística significativa em relação ao gasto energético, bem como à oxidação de carboidratos e lipídios na maior parte do tempo. Os peptídeos leptina e grelina diminuíram após a sobrecarga lipídica, enquanto que o peptídeo YY e a colecistocinina aumentaram, não havendo diferença estatística significativa entre os grupos na maior parte do tempo. Dessa forma, as variáveis estudadas se mostraram independentes do nível de estradiol plasmático. / Climaterium is the phase of women´s life when hormonal alterations occur and lead to peculiar metabolic responses such as a decrease in energy expenditure and weight gain. Thus, the aims of this study were to measure the energy expenditure, calculate carbohydrate and lipid oxidation, at resting and after a lipid overload, of postmenopausal women stratified according to their plasma estradiol value (E2) and evaluate hunger and satiety regulatory peptides in the same moment. Women´s groups were: group 1- E2 39 pg/mL, 2- 40 E2 59 pg/mL, and 3- E2 60 pg/mL. The volunteers received a 1100 kcal and 72% fat meal, which characterized the lipid overload. Energy expenditure was measured by indirect calorimetry for a period of five hours, and measurements were performed at 30, 60, 90, 150, 210 and 270 minutes. The hunger and satiety regulatory peptides were analyzed in the resting, 30 and 270 minutes after the lipid overload. The groups were compared using the nonparametric Kruskal-Wallis test. Linear regression model with mixed effects was used to compare the moments of the same group, considering p<0.05(*). Forty-four postmenopausal women were studied. Their age was 55±5 years (mean±standard deviation), body mass index was 31±4 kg/m² and they were in menopause for 8±7 years. In general, the resting energy expenditure was 1337±194* kcal/day, increasing to 1476±295* kcal/d in the first postprandial 30´, and to 1513±318* kcal/d in the end. There was no statistically significant difference between groups. Regarding carbohydrate oxidation, the baseline value was 151±95 mg/min, decreasing to 146±95 mg/min in the first 30´ and to 122±44 mg/min in the end (values were converted to mg/min for readability). The baseline value of lipid oxidation was 37±30* mg/min, increasing to 52±24* mg/min in the first 30´ and to 63±21* mg/min in the end. There was no statistically significant difference in carbohydrate oxidation between groups, and regarding lipids, the only statistically significant difference was between groups 1 (higher values, p=0,03) and 2 at the end of the experiment, and between groups 1 and 3 (higher values, p=0,04) at time 150´. In relation to the peptides, the baseline leptin was 47±29 ng/mL, decreasing to 44±27 ng/mL within the first postprandial 30´ and to 43±26 ng/mL in the end. Baseline ghrelin was 753±522 pg/mL, decreasing to 705±420 pg/mL in the first 30´ and to 561±343 pg/mL in the end. Baseline peptide YY was 92±40* pg/mL, increasing to 153±63* pg/mL in the first 30´ and to 214±66* pg/mL in the end. Referring to cholecystokinin, the value at 30´ was 1.8±2.3 pg/mL, increasing to 2.2±1.7 pg/mL in the end. Among groups, the only statistically significant difference was related to cholecystokinin between groups 2 and 3 (higher values, p=0,04) in the end. So, after the lipid overload, there was a gradual and significant increase on energy expenditure, predominance of carbohydrate oxidation in relation to the lipids with a decrease on its oxidation, and an increase on lipid oxidation. In regard to comparison between groups, there was no statistically significant difference in relation to energy expenditure, as well as to oxidation of carbohydrates and lipids in most of the time. The peptides leptin and ghrelin decreased after the lipid overload, while peptide YY and cholecystokinin increased, with no statistically significant difference between groups for most of the time. Thus, the variables were independent of plasma estradiol levels.

Le contrôle de la prise alimentaire est un processus complexe et multifactoriel contrôlé par le système nerveux central. Elle est impliquée dans la régulation du poids corporel, la fourniture de substrats énergétiques ainsi que dans l’apport d'un grand nombre de nutriments nécessaires pour couvrir les besoins spécifiques de l'organisme. Parmi tous les facteurs impliqués dans la prise alimentaire, les sensations hédoniques jouent un rôle important dans les choix alimentaires et la limitation de l'ingestion. La partie théorique de cette thèse prend en considération les aspects physio-anatomiques du contrôle de la prise alimentaire, notamment le plaisir sensoriel et son évaluation, dans le cadre des trois phénomènes hédoniques principaux : le rassasiement conditionné (RC), l’alliesthésie alimentaire (AA) et le rassasiement sensoriel spécifique (RSS). La partie expérimentale tente d’évaluer l'impact des diverses manipulations des aliments (ajout de condiments non-caloriques ou caloriques aux aliments simples et aux mets préparés, offrir des condiments de manière successive ou simultanée, alternance des aliments dans un repas) sur les sensations hédoniques et sur la prise alimentaire à court terme. Quatre études ont été réalisées chez des sujets humains des deux genres, de poids normal et en surpoids. La première étude comprenait trois expériences avec des aliments simples suggérant que le rassasiement spécifique et la prise énergétique dépendent des propriétés sensorielles des aliments et donc de la stimulation sensorielle exercée sur les récepteurs oro-pharyngiens. Dans les conditions expérimentales présentes, l'influence du RSS s'est avérée plus importante que celle de l’AA dans la limitation de l’ingestion spécifique. Toutefois, cette limitation par le RSS a pu être repoussée par la modification des propriétés sensorielles de l’aliment consommé jusqu’au rassasiement spécifique : en parallèle avec la re-augmentation du plaisir pour la saveur, l’ingestion était repris lorsqu'un deuxième aliment de saveur distincte était offert, ou lorsque des condiments non-caloriques étaient ajoutés à l'aliment consommé. La deuxième étude reprenait les données de la première en fonction des caractéristiques anthropométriques et démographiques des sujets et mettait en évidence un contrôle hédonique de la prise alimentaire similaire chez les personnes obèses et de poids normal avec des aliments simples non assaisonnés et non transformés. Ces résultats suggèrent que l’impact de la nature et de la présentation des stimuli alimentaires sur la prise alimentaire peut être plus important que celui des traits liés aux personnes, comme le sexe, l'âge ou l'IMC. La troisième étude introduisait une diversité alimentaire soit successive soit simultanée par ajout de condiments à un repas de type « fast food », avec pour effet une augmentation du plaisir alimentaire et des quantités ingérées. La diversité successive a été plus efficace sur l'augmentation de l’ingestion que l'accès simultané aux condiments. Ces résultats laissent penser que le renouvellement de la stimulation sensorielle produirait une perturbation du rassasiement sensoriel spécifique, expliquant l'augmentation de la consommation et pouvant jouer un rôle dans l'actuelle épidémie d'obésité. La quatrième étude évaluait l'impact de différents niveaux d'alternance des aliments. Une alternance modérée dans un repas comprenant deux plats différents augmentait la prise alimentaire à court terme, probablement par suite d'une perturbation de l’habituation sensorielle à une saveur donnée, apportant une explication à l'augmentation de l’ingestion avec des repas sensoriellement variés. Des alternances multiples des aliments diminuaient en revanche la consommation, probablement par l'effet d'une surstimulation sensorielle... / The control of food intake is a complex and multifactorial process controlled by the CNS. It is implicated in the regulation of body weight and the supply of energy substrates, as well as the supply of a panoply of nutrients to cover the specific needs of the organism. Among all the factors involved, hedonic sensations play an important role in guiding food selection and limitation of intake. The theoretical section of this thesis takes into account the physio-anatomical aspects of the control of food intake, in particular sensory pleasure and its evaluation, within the framework of the three principal hedonic phenomena: Conditioned Satiety (CS), Alimentary alliesthesia (AA) and sensory-specific satiety (SSS). The experimental section evaluated the impact of various manipulations of food (adding non-caloric and caloric condiments to simple or prepared foods, offering condiments successively or simultaneously, alternating foods in a meal) on hedonic sensations and on food intake in the short term. Four studies were performed in normal-weight and overweight human subjects of both genders. The first study in three experiments in simple foods suggests that specific satiation and energy intake depend on the sensory properties of foods and thus on the sensory stimulation exerted on oropharyngeal receptors. Under the present experimental conditions, the influence of SSS turned out to be more important than that of AA in limiting specific intake. However, this limitation by SSS could be overridden by modification of the sensory properties of the food eaten to specific satiation: in parallel with the re-increase in pleasure for the flavor, food intake was resumed when a second food with distinctive flavor was offered or when non-caloric condiments were added.The second study re-examined the data of the first one according to anthropometric and demographic characteristics of the population and provided evidence for similar hedonic control of food intake in obese and normal weight persons with simple unseasoned and unprocessed foods. These results suggest that the nature and the presentation of food stimuli impacted food intake more than person-related traits like gender, age or BMI. The third study induced successive and simultaneous sensory variety by adding condiments to ‘fast food’ style meal, and increased food pleasantness and intake. Successive variety was more efficient in increasing intake than simultaneous access to condiments. These results seem to show that renewal in sensory stimulation produces disruption of sensory-specific satiety which may explain the increase of food intake and might be playing a role in the actual obesity epidemic. The fourth study investigated the impact of several levels of alternation of foods. Moderate alternation in a two-course meal increased food intake in the short term, probably by disruption of sensory tuning to a given flavor and may explain the increased intake with sensorily varied meals. Multiple alternations of foods however decreased intake, probably caused by sensory overstimulation. SSS seems to have two opposite intrinsic teleonomies: on the one hand it specifically limits intake of foods eaten, while on the other hand it promotes variety seeking. In this thesis, both functions could be manipulated through simple modifications of the sensory properties of foods or of the way they were offered. In the long term, these kinds of manipulations might compromise a body-mass index medically considered as healthy. The modification of the flavor alone was sufficient to increase pleasure and in turn food intake. The prolongation of intake of the same food when offered with two distinct flavors seems to be related to cerebral representation as two distinct foods. The question on whether sensory pleasure is a sign of usefulness of food stimuli or mere sensory stimulation of the chemical senses may ultimately depend on the nature of the food stimulus.

Partant du constat de la nature encore relativement ambiguë du concept de développement territorial, cette thèse en propose uneapproche à la fois plus rigoureuse et plus large que la simple identification de ce dernier avec le développement économique. Le chemind’analyse choisi s’articule en quatre phases, chacune traitée dans un chapitre différent.Tout d’abord, par le biais d’une brève analyse historique des relations entre la pensée politique, au sens de la gestion des affaires dela cité, et la pensée économique, ce travail met en lumière les raisons qui ont permis au fur et à mesure à la sphère économique de s’imposer,et de revêtir ainsi le rôle de finalité du développement quittant celui de simple instrument. Et, en effet, à certaines conditions, l’amalgamepeut être justifié, notamment en présence d’insuffisance des moyens de chacun pour assurer la couverture de ses propres besoins.Puisque le fait de faire reposer le développement des territoires sur l’aspect économique conduit implicitement à considérer commepérenne cette condition d’insuffisance, nous avons souhaité vérifier si les approches les plus courantes de la théorie économique étaient enmesure de prendre en compte les situations d’opulence. À cette fin, nous avons relâché l’hypothèse de non-satiété, qui est implicite tant dansla convexité des courbes d’indifférence en microéconomie que dans la « loi psychologique » de la Théorie Générale de Keynes.L’élargissement de la théorie économique à la condition de satiété, creusée sur le plan théorique et confrontée à la réalité au cours dela thèse, conduit à avoir un regard très éloigné des représentations habituelles des faits économiques. Et, une fois l’analyse élargie auxrelations entre territoires différents, on peut démontrer, à partir d’une perspective purement économique, la nature contradictoire des finalitéséconomiques du développement.Enfin, adoptant l’optique des territoires comme « construits sociaux », la thèse avance une proposition alternative, fondée sur leslibertés d’être et de faire et leur élargissement progressif, selon une logique voisine de l’approche par les capabilités d’A.Sen, sans pourautant s’y réduire. Cette démarche permet de mettre en cohérence l’économique et le non économique, dans une perspective qui intègrepleinement le concept de durabilité selon la proposition du Rapport Brundtland de 1987 et qui se cristallise dans un nouvel indicateursynthétique de développement, la « création d’espace de développement ». / As the concept of “territorial development” is still relatively ambiguous, this thesis proposes both a more rigorous and widerapproach than merely identifying it with the “economic development on a local area”. Our analysis goes through four distinct phases, each ofthem being dealt with in a different chapter.First, a brief historical analysis of relations between economic and political thoughts, in the sense of community affairsmanagement, emphasizes the reasons which allowed the economic sphere to progressively become more and more influential to the point toestablish itself as the finality of development and go over its status of a “tool”. Indeed, upon certain conditions, this shift can be justified,namely in presence of some scarcity of means in order to satisfy one’s own needs.Because making the concept of territorial development rely only on the economic aspect leads to implicitly consider the condition ofscarcity as permanent, we wished to verify if the current approaches to the economic theory were capable of taking into account the affluenceof developed countries. To this purpose, we relaxed the non-satiety hypothesis, which is implicit both in the convexity of the indifferencecurves in microeconomics and in the “psychological law” of Keynes’ General Theory.The extension of the economic theory to the condition of satiety, which was deeply looked into theoretically and checked against thereality all through the thesis, makes us gain a very unusual insight into economic phenomena. And, once the analysis was opened to therelations between different territories, we were able to demonstrate, from a purely economic point of view, the contradictory nature of theeconomic goals of development.Finally, taking territories as “social constructs”, the thesis suggests an alternative proposition, based on the freedoms to be and tomake, and their progressive enlargement, in a way close to Sen’s capability approach, yet not being a reduction of it. The proposed approachcouples coherently the economic and the non-economic spheres, in a development perspective which integrates completely the concept ofsustainability according to the proposition of the Brundtland Report, 1987, and it is summarized by a new synthetic development index, the“development space creation”.

Dans le contexte général du contrôle du poids, le développement de produits à haut pouvoir satiétogène apparaît comme une alternative intéressante ou une réponse complémentaire aux propositions de régimes réduits en calories. Le principal objectif de cette thèse est d'évaluer le pouvoir satiétogène simple et combinés des fibres et des protéines dans une matrice biscuitière ainsi que l'influence de facteurs psychologiques telle que l'information fournie sur un aliment sur la satiété. Concernant l'influence de paramètres psychologiques, si l'on s'en réfère aux limites du TFEQ couramment utilisées par Stunkard et Messick, une cohorte de jeunes adultes français a de faibles score de TFEQ pour la restriction cognitive, la désinhibition et la faim. Ce résultat nous a permis de proposer de nouvelles limites plus basses que celles couramment utilisées et adaptées à cette catégorie de la population, souvent étudiée dans les études cliniques de comportement alimentaire. Ces limites ont été utilisées pour définir nos groupes de volontaires pour l'étude sur l'effet d'un message sur la satiété. Nous avons conclu qu'un message sur les propriétés satiétogènes d'un produit pourrait influencer un sous-groupe de la population, que sont les femmes faiblement restreintes et fortement désinhibées. Afin d'optimiser la sélection des prototypes utilisés dans l'étude clinique sur l'effet des fibres et des protéines sur la satiété, nous avons développé avec succès un nouvel outil pour entraîner un panel d'experts sensoriels à évaluer leur satiété. Un mélange de fibres et de protéines réduit les sensations d'appétit de manière plus importante que les biscuits enrichis simplement en un des ingrédients. Cette combinaison d'ingrédients actifs stimule des mécanismes qui sont induits par les fibres (comme la réduction de l'insulinémie et le ralentissement de la vidange gastrique) et les protéines (comme la diminution de la glycémie). En conclusion, cette approche intégrative de la satiété a permis d'apporter de nouvelles connaissances sur les effets synergique des fibres et des protéines sur les sensations d'appétit. Nous avons aussi proposé de nouvelles méthodes pour évaluer le pouvoir satiétogène de différents produits en utilisant l'expertise des domaines des sciences du sensoriel et de la nutrition. Ce travail souligne aussi l'importance des aspects psychologiques dans les études de nutrition humaine.Mots clés: Satiété, Fibres, Protéines, Three-Factor Eating questionnaire, Message satiété, entraînement à l'évaluation de la satiété / In the general context of weight management, the development of food with higher satiating power appears to be an interesting alternative or a complementary answer to the proposition of calorie-reduced diets. The main aim of this thesis was to evaluate the single and combined satiating effects of proteins and fibres in biscuits and the influence of psychological factors, such as a given message about a food, on satiety. As for cognitive parameters, considering Stunkard and Messick guidelines about TFEQ limits, young French adults aged 20–39 yrs have low cognitive restraint, disinhibition and hunger scores. This finding makes it possible to suggest new limits for the TFEQ scores better adapted to this category of the population which is often used in clinical studies. We used these limits to define our groups of volunteers in the study about the influence of a message on satiety. It was found that giving a message on the satiating potential of a food may affect a sub-group of the population, such as low-restrained high-disinhibited women. To optimize the selection of the prototypes used in the clinical study about fibre and protein effects on satiety, we developed a new successful methodology to train a panel of sensorial experts in satiety assessment. A combination of fibre and protein in biscuits reduces appetite sensations more than do single enrichment in fibre or protein. The mixing of fibre and protein activates mechanisms which are induced by fibre (such as reduced insulinemia and slowed gastric emptying) and protein (such as reduced glycaemia). In conclusion, this integrative approach on satiety brings new knowledge about the synergistic effect of fibre and protein on appetite sensations. It proposes a new methodology using sensory and nutrition expertise to assess the satiety power of products and it also highlights the importance of psychometric traits in human food studies.Key words: Satiety, Fibres, Proteins, Three-Factor Eating questionnaire, Satiety message, training in satiety assessment

Fractionner son alimentation consiste à augmenter la fréquence de ses prises alimentaires, sans modifier la quantité totale d’énergie ingérée. Dans ce travail de thèse, nous avons étudié les effets du fractionnement alimentaire sur l’appétit et la balance énergétique chez des sujets de poids normal et obèses. Le premier objectif était d’ordre méthodologique : nous avons proposé et validé un dispositif original d’étude de l’appétit, basé sur la duplication du même protocole dans deux lieux de recherche différents et sur l’utilisation d’un restaurant expérimental, en reproduisant une situation écologique de repas. Ce dispositif permet de répondre à deux enjeux méthodologiques. D’une part, il permet une approche intégrée de l’appétit, grâce à l’association de mesures subjectives (sensations de faim et de satiété), physiologiques (biomarqueurs de l’appétit : ghréline et GLP-1) et comportementales (consommations, choix et rythmes alimentaires). D’autre part, le caractère écologique de la situation de repas proposée assure une bonne validité externe des résultats. Le second objectif était d’étudier, grâce à cette méthodologie, les conséquences à court terme du fractionnement alimentaire sur les sensations de faim, les hormones qui régulent l’appétit, le comportement au cours du repas qui suit le fractionnement, ainsi que sur les orientations métaboliques. Chez des sujets de poids normal, les approches subjectives, physiologiques et comportementales ont toutes montré une diminution de l’appétit en réponse au fractionnement. En revanche, nous n’avons pas obtenu les mêmes bénéfices comportementaux chez les obèses, chez qui le fractionnement n’a pas induit de baisse des apports énergétiques au cours du repas suivant. Sur le plan métabolique, nous avons montré les mêmes effets dans les deux populations, à savoir une insulinémie maintenue au-dessus de son niveau basal, entraînant une inhibition prolongée de la lipolyse, elle-même caractérisée par une baisse des concentrations plasmatiques en acides gras non estérifiés. Le fractionnement a également entrainé une diminution de la dépense énergétique via la thermogénèse alimentaire. Ce travail met en évidence les bénéfices possibles du fractionnement alimentaire chez les personnes de poids normal pour mieux contrôler leur appétit. En revanche, cette stratégie ne semble pas adaptée pour des personnes obèses. Les effets sur la dépense énergétique et les orientations métaboliques, potentiellement négatifs, doivent être étudiés sur de plus longues périodes / This thesis project consists in studying the effects of eating smaller more frequent meals, with no change in energy intake, on appetite and energy balance in normal weight and obese subjects. The first objective was methodological: we proposed and validated an original methodology for studying appetite, based on the duplication of the same protocol in two different research centers, and the use of an experimental restaurant, reproducing an ecological meal situation. This methodology enables to answer two methodological issues. Firstly, it allows an integrated approach of appetite, associating subjective (hunger and satiety feelings), physiological (biomarkers of appetite: ghrelin and GLP -1) and behavioral (food intake, choices and eating rhythms) measurements. Secondly, the ecological character of the eating situation we proposed, ensure a good external validity of the results. The second objective was to assess, thanks to this methodology, the short term consequences of eating smaller more frequent meals on subjective appetite, on hormones that regulates appetite, on eating behaviors during the subsequent meal, and on metabolic orientations. In normal weight subjects, subjective, physiological and behavioral approaches showed a decrease in appetite after eating smaller more frequent meals, while in obese subjects we did not obtain the same beneficial behaviors: obese subjects did not consume less energy during the subsequent meal. Metabolic results showed the same effects in both normal weight and obese subjects: insulin concentrations were maintained above their basal level, leading to an extended inhibition of lipolysis, characterized by a decrease in plasmatic concentrations of non-esterified fatty acids. Eating smaller more frequent meals also decreased energy expenditure via diet induced thermogenesis. This work highlights the fact that eating smaller more frequent meals may be beneficial in normal weight individuals in order to better control appetite, but it does not seem to be an adequate strategy in obese individuals. The effects on energy expenditure and metabolic orientations, potentially negative, should be studied over a longer period

La concentration en protéines des grains est un critère qualitatif majeur qui conditionne la valeur économique et technologique du blé tendre (Triticum aestivum L.). Cependant, la forte relation négative existant entre concentration en protéines et rendement en grains implique que l’amélioration de la concentration en protéines par une approche génétique soit complexe à atteindre sans impacter négativement le rendement. Pour contourner cette difficulté, il a été proposé qu’une sélection variétale basée sur l’écart à cette relation négative (nommé Grain Protein Deviation ; GPD) permette d’améliorer la concentration en protéines indépendamment du rendement. Au niveau physiologique, le GPD est fortement corrélé à la capacité des génotypes à absorber de l’azote après floraison indépendamment de la quantité d’azote déjà absorbée à floraison, suggérant que la satiété en azote soit à la base de son établissement. Envisager une sélection sur la base du GPD nécessite cependant d’acquérir des connaissances approfondies des mécanismes impliqués dans la régulation de l’absorption d’azote par la satiété en azote, qui permettraient de cibler précisément des traits simples à quantifier et robustement associés à cette capacité accrue d’accumulation de protéines dans les grains.Cette étude se base sur deux expérimentations conduites en conditions contrôlées et une expérimentation au champ. Dans chacune de ces expérimentations, différents niveaux de fertilisation ont été appliqués en pré-floraison afin d’obtenir des statuts azotés contrastés à floraison. L’effet du statut azoté à floraison sur l’absorption post-floraison a ensuite été observé dans différentes conditions de disponibilités d’azote après floraison. Des mesures physiologiques et moléculaires ont été réalisées en parallèle des mesures d’absorption d’azote.Nous avons mis en évidence que l’absorption d’azote post-floraison présente une dynamique élaborée qui suppose qu’elle est soumise à des régulations complexes. Parmi celles-ci, le statut azoté des plantes à floraison conditionne en grande part la quantité d’azote absorbée dans les jours qui suivent la floraison (PANUprécoce , de floraison à floraison + 250 degrés-jour). La quantité de PANUprécoce se présente comme un déterminant fort de la concentration en protéines des grains du fait de la forte corrélation positive observée entre ces deux traits en conditions contrôlées et au champ, et ce indépendamment du niveau de rendement. L’étude de deux génotypes robustement contrastés pour le GPD a montré qu’à statuts azotés équivalents, la quantité de PANUprécoce est sujette à des effets génétiques qui tendent à confirmer l’impact de la variabilité génétique de satiété en azote sur l’établissement du GPD.Ces travaux ont permis de proposer des marqueurs du GPD potentiellement valorisables en sélection. Au niveau physiologique, la croissance des tiges après floraison se présente comme un marqueur prometteur du GPD car ce trait est fortement corrélé à la PANUprécoce. Au niveau moléculaire, la concentration en nitrates des racines, également soumise à des effets génétiques, est proposée comme marqueur potentiel du fait de son rôle probable dans la régulation expressionnelle des gènes impliqués dans l’absorption et l’assimilation d’azote. / Grain protein concentration is one of the major qualitative criteria of bread wheat (Triticum aestivum L.) economic and technological value. However, the negative relationship existing between protein concentration and grain yield implies that grain protein concentration improvement is complex to achieve without detrimental effect on grain yield. Breeding programs based on the deviation to this negative relationship (Grain protein deviation of GPD) have been proposed to be a suitable strategy to improve grain nitrogen concentration without detrimental effects on yield. At a physiological level, GPD is strongly correlated with genotypes aptitude to uptake nitrogen after flowering independently of the nitrogen amount already taken up before this stage, suggesting that satiety for nitrogen could be involved in its establishment. Breeding for GPD implies however a more detailed knowledge of the processes implied in nitrogen uptake regulation by nitrogen plant satiety. This would allow targeting traits both simple to measure and robustly associated with this increased capacity to accumulate proteins in grains.The present study is based on two experiments carried on under controlled conditions and a third led under field conditions. In all experiments, various levels of pre-flowering fertilization were applied in order to obtain contrasted plant nitrogen status at flowering. Nitrogen status effect on post-flowering nitrogen uptake was observed under various post-flowering N availability conditions. Physiological and molecular measurements were carried out in parallel with uptake measurements.We highlighted that post-flowering nitrogen uptake has an elaborate dynamic, suggesting the involvement of complex regulations. Among these, plant nitrogen status at flowering determines to a great extent the amount of nitrogen taken up during the days following flowering (early PANU, from flowering to flowering +250 °C.days-1). Early PANU appears to be a strong determinant of grain protein concentration, as strong positive correlations were observed between these two traits both under controlled conditions and field conditions, independently of grain yield level. The study of two genotypes strongly contrasted for GPD highlighted that, despite comparable N status, early PANU is subjected to strong genetic variations which tend to identify N satiety as a determinant of GPD.The present study identified robust markers of GPD of potential use in plant breeding. At a physiological level, post flowering stem elongation appears to be a promising marker of GPD since this trait is strongly correlated with early PANU. At a molecular level, root nitrate concentration, a trait submitted to genetic variations, is also proposed as a marker of GPD because of its role in the expression regulation of the genes governing nitrogen uptake and assimilation.

Nous passons plus des trois quarts de notre vie dans l'état postprandial. Pourtant, une plus grande attention a été accordée à l'étude du métabolisme à jeun qu'à l'impact de l'état postprandial sur la santé.Il est prouvé scientifiquement qu'une alimentation optimale pour la santé passe par la prise en compte de l'impact glycémique des aliments au-delà de leur simple teneur en glucides. Un déterminant important de l'impact glycémique de notre alimentation est l'amidon, qui joue un rôle clé dans la nutrition humaine en fournissant jusqu'à 50% de l'apport énergétique total. S'il est établi que la cinétique de digestion des aliments riches en amidon est un élément essentiel de leur impact glycémique, les contributions de chaque étape digestive à ce processus restent un sujet de débats. Afin de mieux comprendre les facteurs qui peuvent influencer la réponse glycémique aux aliments riches en amidon, et d’identifier de nouvelles stratégies pour atténuer leur impact glycémique, il est essentiel d'élargir notre compréhension du processus digestif de l'amidon. Cette thèse visait à étudier la digestion de repasriches en amidon (pain et pâtes), à réévaluer la contribution l’amylase salivaire à l'aide de digestions semi-dynamiques in vitro, et à mener une étude chez l'Homme pour déterminer l'effet de boissons (jus de citron et thé) sur : la réponse glycémique au pain, l'apport ad libitum, et la digestion gastrique étudiée par imagerie par résonance magnétique (IRM). Nos résultats apportent une base scientifique à l'élaboration d'une stratégie simple et efficace pour réduire la réponse glycémique aux aliments riches en amidon dans des repas de tous les jours. / All of us spend over three quarters of our lives in the postprandial state. Still, more attention has been dedicated to the study of the fasting metabolism than to the impact of the postprandial state on health.Scientific evidence supports that an optimum diet for health requires consideration of the glycaemic impact of foods in preference to consideration of carbohydrate content alone. An important determinant of the glycaemic impactof our diets is starch, which plays a key role in human nutrition, supplying up to 50% of the total energy intake. If it is clear that the digestion rate of starch-rich foods is an important determinant of their glycaemic impact, the contribution of each digestive stage to this process remains controversy. To better understand the factors that can influence the glycaemic response to starch-rich foods, and to identify new strategies to attenuate the glycaemic impact of starch-rich diets, it is essential to expand our understanding of thedigestive process of starch. The aims of this PhD were to study the digestionof starch-rich meals (bread and pasta), to reevaluate the contribution of salivary amylase using semi-dynamic in vitro digestions, and to conduct a human study to determine the effect of drinks (lemon juice and tea) on: the glycaemic response to bread, ad libitum intake, and gastric digestion assessed by magnetic resonance imaging (MRI). Our results provide scientific rationale for the development of a simple and effective strategy to reduce the glycaemicresponse to starch-rich foods in everyday-life meals.

A cada dia cresce o interesse por alimentos ricos em carboidratos não disponíveis em virtude da relação inversa entre seu consumo e o risco de doenças crônicas não transmissíveis (DCNT). No presente trabalho, foi avaliado o potencial fisiológico da farinha de banana verde (FBV) como ingrediente funcional. Em ratos adultos, foi realizado ensaio de média duração (28 dias) para avaliação do efeito trófico da FBV sobre o intestino grosso e de parâmetros relacionados à tolerância à glicose. Em humanos, foram realizados ensaios clínicos de curta e média duração para avaliação dos efeitos sobre resposta glicêmica; liberação de hormônios gastrintestinais relacionados à saciedade; status antioxidante; fome e saciedade; e funcionamento intestinal. A FBV foi produzida com banana verde, Musa acuminata, de acordo com patente depositada pelo grupo (Patente (RPI - 1941), 2008). A FBV é uma fonte concentrada de carboidratos não disponíveis, com 56% de AR e 8% de FAT na base integral. A adição de FBV nas rações provocou efeito trófico no ceco dos animais, evidenciado por aumento no índice metafásico, número de células da cripta e profundidade das criptas. Além disso, a ração com FBV proporcionou melhora nos parâmetros relacionados à tolerância à glicose. Em voluntários saudáveis, a ingestão de uma única refeição adicionada de 8 g de FBV proporcionou aumento na saciedade e boa correlação entre os parâmetros fome/saciedade e níveis plasmáticos de grelina e insulina, melhorou o funcionamento intestinal, além de resultar em alta fermentabilidade in vitro em relação à lactulose. Após ingestão diária da FBV por 14 dias, os resultados da ingestão de RC0 (refeição controle antes do tratamento) e de RC14 (RC0 após 14 dias de tratamento) mostraram que ocorre melhora na tolerância à glicose, evidenciada pela menor liberação de insulina durante o GTT. O efeito positivo sobre funcionamento intestinal, sobre saciedade e sobre liberação de hormônios gastrintestinais no plasma permaneceu após ingestão prolongada da FBV. A adição da FBV na refeição resultou em aumento da capacidade antioxidante in vitro. A FBV apresenta inúmeros atributos positivos para elaboração de produtos que ampliem as opções para uma alimentação saudável, bem como propiciem saúde intestinal, visando a diminuição do risco de DCNT. / The study of unavailable carbohydrates has been of great concern due to their inverse relation with the risk for non-transmissible chronic diseases (NTCD). In the present study, the functional potential of unripe banana flour (UBF) was evaluated. In rats, a medium-term assay was carried in order to evaluate parameters related to glucose tolerance and the trophic effect of UBF on the large bowel. In healthy volunteers, short and medium-term clinical assays were carried to evaluate the effects of UBF on glycemic response; release of gastrointestinal hormones related to satiety (ghrelin, leptin and insulin); antioxidant status; hunger and satiety; and intestinal health. UBF was produced with unripe banana, Musa acuminata, subgroup Cavendish, maturation stage I, in industrial scale and according to a patent deposited by the group (Patent (RPI - 1941), 2008). UBF is a concentrated source of unavailable carbohydrates, with 56% RS and 8% DF (wet weight). Adding UBF in rat rations resulted in a trophic effect in the animals\' cecum, which was evidenced by increase in the metaphasic index, number of crypt cells and crypt depth. Moreover, the ration with UBF resulted in better glucose tolerance parameters. In healthy volunteers, adding UBF (8 g) to an only meal provided significant satiety and good correlation between the parameters hunger/ satiety and plasmatic levels of ghrelin and insulin, improved bowel habit, as well as resulted in high in vitro fermentability in relation to lactulose. After daily intake of UBF for 14 days, the results of the intake of RC0 (control meal before treatment) and RC14 (RC0 after 14 days treatment) showed that there is a positive post-prandial variation in the plasmatic concentrations of gastrointestinal hormones, as well as improvement in glucose tolerance, evidenced by lower insulin release during GTT. The positive effect on bowel habit, satiety and release of gastrointestinal hormones in plasma was kept after prolonged intake of UBF. Adding UBF to the meal provided significant increase in the in vitro antioxidant capacity. UBF presents several positive attributes for the elaboration of products that may increase the options for healthy eating habits, as well as provide intestinal health, always aiming to decrease the risk for NTCD.