yes / Over the past 30 years, the understanding of eating behaviour has been dominated by the concept of dietary restraint. However, the development of the Three Factor Eating Questionnaire introduced two other factors, Disinhibition and Hunger, which have not received as much recognition in the literature. The objective of this review was to explore the relationship of the Disinhibition factor with weight regulation, food choice and eating disorders, and to consider its aetiology. The review indicates that Disinhibition is an important eating behaviour trait. It is associated not only with a higher body mass index and obesity, but also with mediating variables, such as less healthful food choices, which contribute to overweight/obesity and poorer health. Disinhibition is also implicated in eating disorders and contributes to eating disorder severity. It has been demonstrated that Disinhibition is predictive of poorer success at weight loss, and of weight regain after weight loss regimes and is associated with lower self-esteem, low physical activity and poor psychological health. Disinhibition therefore emerges as an important and dynamic trait, with influences that go beyond eating behaviour and incorporate other behaviours which contribute to weight regulation and obesity. The characteristics of Disinhibition itself therefore reflect many components representative of a thrifty type of physiology. We propose that the trait of Disinhibition be more appropriately renamed as ¿opportunistic eating¿ or ¿thrifty behaviour¿.

Yes / The WNT pathway was shown to play an important role in the adult central nervous system. We previously identified the WNT pathway as a novel integration site of the adipokine leptin in mediating its neuroendocrine control of metabolism in obese mice. Here we investigated the implication of WNT signaling in seasonal body weight regulation exhibited by the Djungarian hamster (Phodopus sungorus), a seasonal mammal that exhibits profound annual changes in leptin sensitivity. We furthermore investigated whether crucial components of the WNT pathway are regulated in a diurnal manner. Gene expression of key components of the WNT pathway in the hypothalamus of hamsters acclimated to either long day (LD) or short day (SD) photoperiod was analyzed by in situ hybridization. We detected elevated expression of the genes WNT-4, Axin-2, Cyclin-D1, and SFRP-2, in the hypothalamic arcuate nucleus, a key energy balance integration site, during LD compared with SD as well as a diurnal regulation of Axin-2, Cyclin-D1, and DKK-3. Investigating the effect of photoperiod as well as leptin on the activation (phosphorylation) of the WNT coreceptor LRP-6-(Ser1490) by immunohistochemistry, we found elevated activity in the arcuate nucleus during LD relative to SD as well as after leptin treatment (2 mg/kg body weight). These findings indicate that differential WNT signaling may be associated with seasonal body weight regulation and is partially regulated in a diurnal manner in the adult brain. Furthermore, they suggest that this pathway plays a key role in the neuroendocrine regulation of body weight and integration of the leptin signal.

Problematic weight regulation as found in obesity and Anorexia Nervosa (AN) are chronic conditions which require long-term management. In order to develop long-term strategies to manage these conditions, a clearer understanding of the factors that can contribute to the development and also recovery from these conditions are a necessity. Although obesity and AN are at the opposite end of the bodyweight spectrum, some shared psychological processes may drive these states. One factor that has been suggested to contribute to problematic weight regulation is psychosocial stress whilst positive affect systems and affect regulation processes are important for regulating stress-related experiences. Gilbert (2005) describes an affect regulation system which consists of two positive affect systems known as social rank and attachment. Whilst the latter affect system refers to the attachment bond that develops between an infant and its caregiver (which extends to adult relationships), the former is used to form relationships that allow us to compete for limited resources and maintain our status in the social environment. Affect regulation processes in the current research are self-criticism and self-reassurance. Whilst self-critical thoughts and feelings can be triggered by perceptions of being low rank, the idea that people can be self-reassuring or being able to self-reassure at times of difficulty is nested in the positive infant-caregiver attachment bond and a consequence of internalizing parental soothing (Gilbert, 2006). Hence, as stress is suggested to be an important factor in problematic weight regulation and affect systems and processes are central to the regulation of emotional responses to stress-related experiences, the current series of studies examined these factors in relation to problematic weight regulation. The current research consisted of four studies designed to examine the role of stress and affect regulation in relation to weight change, weight regain following weight loss and recovery versus symptom maintenance in AN in women. A longitudinal study (Study One) was conducted to examine the change trajectories of stress, eating pathology and bodyweight, how these changes influence each other and the role of affect regulation systems and processes on these changes in a community based sample (N = 1157). Study Two examined the role of stress and affect regulation as predictors of weight regain in those who have lost weight (N = 42) and Study Three used a measure of life events and difficulties to investigate the role of stressful life changes and affect systems on recovery and relapse following AN (N = 30). Finally, in Study four, an expressive writing task which has been demonstrated to have a positive impact on stress-related health outcomes was used to explore the role of stress, affect systems and processes on problematic weight regulation and eating at times of stress (N = 57). The findings of the research studies demonstrated that there is a concurrent link between stress and the regulation of bodyweight and eating in a community-based sample of women. However, the proposed relationship between stress, bodyweight and eating behaviours was not confirmed when examined longitudinally in a community-based sample, over a 7-month period in women who have lost weight or when examined retrospectively as contributing to symptom maintenance in women with AN. However, the main finding of the current series of studies suggested that affect systems and affect regulation processes do have important implications for regulating stress-related experiences, bodyweight and eating behaviours. Perceived low social status, greater insecurity of attachment, more self-critical and less self-reassuring thoughts and feelings were related to increases in stress levels, higher bodyweight and higher levels of dysfunctional eating patterns. In addition, whilst expressive writing did not reduce stress, influence bodyweight or improve affect regulation at times of difficulty, writing about positive experiences had a positive impact on reducing dietary restraint behaviours during a stressful period. In conclusion, these findings suggest that it may not be stress per se that contributes to unhealthy changes in bodyweight and eating behaviours but how we use our affect systems and processes to manage our emotions at times of difficulty. Consequently, these findings have important implications for practice as weight loss programmes, Eating Disorder prevention programmes and stress management interventions should address the issues of perceived low social status, self-criticism and attachment insecurities.

Réguler la prise alimentaire et la dépense énergétique permet en général de limiter d'importants changements de poids corporel. Hormones (leptine, ghréline, insuline) et nutriments sont impliqués dans ces régulations. La résistance à la leptine, souvent associée à l'obésité, limite la régulation de la prise alimentaire. La modélisation mathématique de la dynamique du poids contribue en particulier à une meilleure compréhension des mécanismes de régulation (notamment chez l’humain). Or les régulations hormonales sont largement ignorées dans les modèles existants.Dans cette thèse, nous considérons un modèle de régulation hormonale du poids appliqué aux rats, composé d'équations différentielles non-linéaires. Il décrit la dynamique de la prise alimentaire, du poids et de la dépense énergétique, régulés par la leptine, la ghréline et le glucose. Il reproduit et prédit l'évolution du poids et de la prise alimentaire chez des rats soumis à différents régimes hypocaloriques, et met en évidence l'adaptation de la dépense énergétique. Nous introduisons ensuite le premier modèle décrivant le développement de la résistance à la leptine, prenant en compte la régulation de la prise alimentaire par la leptine et ses récepteurs. Nous montrons que des perturbations de la prise alimentaire, ou de la concentration en leptine, peuvent rendre un individu sain résistant à la leptine et obèse. Enfin, nous présentons une simplification réaliste de la dynamique du poids dans ces modèles, permettant de construire un nouveau modèle combinant les deux modèles précédents / The regulation of food intake and energy expenditure usually limits important loss or gain of body weight. Hormones (leptin, ghrelin, insulin) and nutrients (glucose, triglycerides) are among the main regulators of food intake. Leptin is also involved in leptin resistance, often associated with obesity and characterized by a reduced efficacy to regulate food intake. Mathematical models describing the dynamics of body weight have been used to assist clinical weight loss interventions or to study an experimentally inaccessible phenomenon, such as starvation experiments in humans. Modeling of the effect of hormones on body weight has however been largely ignored.In this thesis, we first consider a model of body weight regulation by hormones in rats, made of nonlinear differential equations. It describes the dynamics of food intake, body weight and energy expenditure, regulated by leptin, ghrelin and glucose. It is able to reproduce and predict the evolution of body weight and food intake in rats submitted to different patterns of caloric restriction, showing the importance of the adaptation of energy expenditure. Second, we introduce the first model of leptin resistance development, based on the regulation of food intake by leptin and leptin receptors. We show that healthy individuals may become leptin resistant and obese due to perturbations in food intake or leptin concentration. Finally, modifications of these models are presented, characterized by simplified yet realistic body weight dynamics. The models prove able to fit the previous, as well as new sets of experimental data and allow to build a complete model combining both previous models regulatory mechanisms

The purpose of this study was to determine if the students in the 5th grade class at Granite Hill Elementary were overweight or obese. The research questions included: (a) Does the Granite Hill Elementary School population mirror the world wide trend of increasing childhood overweight and childhood obesity, and (b) how does the Granite Hill Elementary School population compare to the International Obesity Task Force standards?

Die Regulation der Nahrungsaufnahme erfolgt zentral im Hypothalamus wo eine Vielzahl von G-Protein-gekoppelten Rezeptoren exprimiert werden die an der Gewichtsregulation beteiligt sind. Periphere hormonelle Signale aktivieren ihre korrespondierenden Rezeptoren im Nucleus arcuatus (ARC) oder im Nucleus paraventricularis (PVN) und modifizieren dadurch sowohl das anorexigene System, z.B. über die Stimulation des Melanocortin-4-Rezeptors (MC4R) im PVN, als auch das orexigene System mit dem Neuropeptide Y (NPY) sowie dem Agouti-related Protein (AgRP). Im Zuge einer systematischen Interaktionsstudie wurden verschiedene GPCRs, die entweder mit dem MC3R oder dem MC4R auf dem gleichen Neuron koexprimiert werden und nachweißlich die Appetit- und Gewichtregulation beeinflussen, untersucht. Basierend auf den Ergebnissen von Sandwich-ELISA und FRET- (Fluoreszenz-Energie-Transfer)Studien konnte eine Interaktion des MC3R mit dem Growth hormone secretagogues Rezeptor (GHSR) bestimmt werden, die beide auf den NPY/AgRP-Neuronen des ARC lokalisiert sind. Der MC3R gehört zu den Gαs bindenden Rezeptoren wohingegen GHSR über den Gαq vermittelten Signaltransduktionsweg signalisiert. Es konnte eine Erhöhung der induzierten cAMP-Spiegel infolge der Stimulation des MC3R sowohl mit α-, als auch β- und γ-MSH für die Koexpression von MC3R mit GHSR im Vergleich zum MC3R Homodimer ermittelt werden. Die Charakterisierung des neuen Signalisierungsverhaltens des Heterodimers unter der Verwendung verschiedener Inhibitoren zeigte eine Aktivierung von Gαi in Gegenwart der endogenen Agonisten beider Rezeptoren. Die Beobachtung unterschiedlicher Regulationsmuster nach der Kostimulation des Heterodimers in Abhängigkeit von α- oder γ-MSH jeweils in Anwesenheit von Ghrelin verweist auf komplexe Interaktionsmechanismen zwischen dem Melanocortin- und dem Ghrelin-Rezeptor innerhalb der hypothalamischen Gewichtsregulation. / Food intake is centrally regulated in hypothalamic nuclei where many GPCRs are expressed which are known to be involved in weight regulation.Peripheral hormonal signals activate their corresponding receptors in the arcuate nucleus (ARC) or paraventricular nucleus (PVN) and modulate the orexigenic (appetite-supressing) pathway mediated by stimulation of the melanocortin-4-receptor (MC4R) as well as the anorexigenic (appetite-stimulating) pathway including neuropeptide Y (NPY) and agouti-related protein (AgRP). In a systematic approach we investigated the interaction of a selective number of GPCRs which are co-expressed on the same neurons like MC3R or MC4R and know to play an essential role in hypothalamic weight regulation. Based on the results of a sandwich ELISA and fluorescence resonance energy transfer (FRET) approach we report the interaction of the MC3R and the growth hormone secretagogue receptor (GHSR) which are co-expressed on arcuate NPY/AgRP neurons. It is known that MC3R couple to the Gαs whereas GHSR couple to the Gαq signaling pathway. However, here the co-expression of MC3R and GHSR reveal a profoundly increase cAMP-accumulation after melanocortin (α-, β- and γ-MSH) challenge, that is higher compared to MC3R activation alone. In-depth characterization of the new signaling properties of the MC3R/GHSR heterodimer by different inhibitors revealed the activation of Gαi in the presents of both endogene agonists. The observation of different regulatory pattern after co-stimulation of the heterodimer depending on the endogenouse ligands (α- or γ-MSH) of MC3R reflect complex functional interaction mechanisms between melanocortin and ghrelin receptors within the hypothalamic signaling pathways of weight regulation.

Thesis (MSc Nutrition Science)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: First-year female students (FYFS), studying at the University of Stellenbosch were previously identified as a high-risk group for gaining weight. A four-year follow-up of these female students indicated that a large percentage experience weight fluctuations throughout their university careers. The unique weight management needs of the FYFS were also identified in the longitudinal study. The integration of these results with an extensive search and assessment of the weight management literature led to the development of a multidimensional weight-management paradigm for application in the development of weight-management interventions for female students. Subsequently, a self-help weight-management manual, which follows the multidimensional approach proposed in the mentioned paradigm, was developed to address the unique weight-management needs of female students. The aim of the current study was to evaluate the impact of the multidimensional self-help weightmanagement manual (the Manual) on the weight status and associated factors of FYFS at the University of Stellenbosch over an eight-month period. For this purpose a non-randomized quasi-experimental design was used, including purposively selected experimental and control groups. Data were obtained during February (Baseline), May (three months after baseline = Follow-up I) and October 2002 (eight months after baseline = Follow-up 2). All students in the experimental group received the Manual at Baseline for use during the eight-month study period. Because this was a low-intensity intervention programme, no further contact was made with either group during the study period, except when Followup I data were obtained. Measures that were taken and instruments that were completed include the following: weight, height, triceps skinfoid, mid-upper ann circumference, hip circumference, waist circumference, Adolescent Self-Concept Scale (self-concept), Body Shape Questionnaire (body shape concerns), Eating Attitudes Test (eating attitudes and behaviours), General Health Questionnaire (general psychological well-being), 90-item Semi-quantified Food Frequency Questionnaire (dietary intake from nine food groups), and the Baecke Questionnaire of Habitual Physical Activity (physical activity). Additional questions on weight related perceptions and practices, dissatisfaction with body parts, reasons for eating and socio-demographic factors were also included. The Baseline characteristics of the FYFS involved in this study, which did not differ between the experimental and control groups for all key variables, identified them as a typical group of young female adults who are healthy but are not realistic about their weight status and who experience numerous problems related to their weight status. The implementation of the Manual was found to be significantly effective in limiting weight gain among the FYFS in the experimental group. The control group experienced almost a full unit increase in BMI (0.93 kg/m²), while the increase found for experimental group was 0.53 kg/m² (p=0.004). Although the weight of both groups increased initially the experimental group went on to lose weight, while the control group continued to gain weight during the last five months of the intervention. The impact of the Manual is further illustrated by the fact that the FYFS in the experimental group who indicated that they did Lise the Manual extensively experienced a significantly lower rise in their weight (change in BMI over study period = 0.37 kg/m²) than those in the experimental group who indicated that they did not use the Manual (change in BMI over study period = 0.89 kg/m²). Factors that are possibly linked to the success attained with the Manual were identified and include more reasonable weight goals; the use of sound weightreduction methods such as a balanced diet and physical activity; improvements in self-concept; maintenance of physical activity levels, especially during the first three months at university; improvement in general psychological well-being; decreased intake of foods from the "other" (includes mainly high fat, sugar based foods such as doughnuts, cookies, cake, tart), beverage and grains food groups; and possibly less concerns with body shape from the start. Factors for which no link with weight management success could be established include changes in body composition; perceptions of own weight; weight loss attempts; foods from the vegetables, fruit, milk and cheese, meat, fish and chicken, fats and fast foods food groups; physical activity over the total eight-month period; reasons for eating; eating attitudes and behaviour; dissatisfaction with body parts; and body shape concerns. It is recommended that the implementation of the Manual on the campus of the University of Stellenbosch to prevent weight gain of FYFS should be considered, bearing in mind some of the recommendations formulated by the FYFS in the experimental group. / AFRIKAANSE OPSOMMING: Eerstejaar damestudente wat aan die Universiteit van Stellenbosch studeer is voorheen geïdentifiseer as 'n hoë risiko groep vir gewigstoename. 'n Vier-jaar opvolg van hierdie damestudente het aangedui dat 'n groot persentasie vir die duur van hul universiteitsloopbane gewigsfluktuasies ondervind. Die unieke gewigshanteringsbehoeftes van die eerstejaar damestudente is ook tydens die longitudinale studie geïdentifiseer. Die integrasie van hierdie resultate met 'n uitgebreide soektog en ontleding van die literatuur wat betrekking het op gewigshantering het aanleiding gegee tot die ontwikkeling van 'n multidimensionele gewigshanteringsparadigma wat gebruik kan word tydens die ontwikkeling van gewigshanteringsintervensies vir damestudente. As 'n volgende stap is 'n self-help gewigshanterings handleiding, wat die multidimensionele benadering voorgestel in die genoemde paradigma volg, ontwikkelom die unieke gewigshanteringsbehoeftes van damestudente aan te spreek. Die doel van die huidige studie was om die impak van die multidimensionele self-help gewigshanteringshandleiding (die Handleiding) op die gewigstatus en geassosieerde faktore van eerstejaar damestudente aan die Universiteit van Stellenbosch oor 'n tydperk van agt maande, te evalueer. Vir hierdie doeleinde is 'n nie-gerandomiseerde kwasi-eksperimentele ontwerp gebruik, wat doelbewus geselekteerde eksperimentele en kontrole groepe ingesluit het. Data is gedurende Februarie (Basislyn), Mei (drie maande na basislyn = Opvolg-I) en Oktober (agt maande na basislyn = Opvolg-2) 2002 versamel. Alle studente in die eksperimentele group het die Handleiding tydens Basislyn ontvang vir gebruik tydens die agt maande studieperiode. Omdat dit 'n lae-intensiteit intervensie program was, is geen verdere kontak gedurende die studieperiode met beide die groepe gemaak nie, behalwe tydens die versameling van Opvolg-I data. Metings wat geneem is en instrumente wat voltooi is, sluit die volgende in: gewig, lengte, triseps velvou, mid-bo-armomtrek, heupomtrek, middelomtrek, "Adolescent Self- Concept Scale" (self-konsep), "Body Shape Questionnaire" (besorgdheid oor liggaamsvorm), "Eating Attitudes Test" (eetgedrag en -houding), "General Health Questionnaire" (algemene sielkundige welstand), 90-item semi-gekwantifiseerde voedselfrekwensievraelys (dieetinname van nege voedselgroepe), en die "Baecke Questionnaire of Habitual Physical Activity" (fisieke aktiwiteit). Addisionele vrae aangaande gewigsverwante persepsies en praktyke, ontevredenheid met liggaamsdele, redes vir eet en sosio-demografiese faktore is ook ingesluit. Die Basislyn eienskappe van die eerstejaar damesstudente wat aan hierdie studie deelgeneem het, het nie tussen die eksperimentele en kontrole groepe vir alle sleutelveranderlikes verskil nie. Hierdie inligting het ook daarop gedui dat die studente 'n tipiese groep jong vroulike volwassenes is wat gesond is maar, onrealisties is oor hul gewigstatus en baie gewigstatusverwante probleme ondervind. Die resultate toon dat die implementering van die Handleiding beduidend effektief was om die gewigstoename by eerstejaar damestudente in die eksperimentele groep te beperk. Die gewig van die kontrole groep het byna 'n volle LMI eenheid (0.93 kg/m²) toegeneem terwyl die toename vir die eksperimentele groep 0.53 kg/m² was. Alhoewel die gewig van beide groepe aanvanklik toegeneem het, het die eksperimentele groep daarna gewig verloor terwyl die kontrole groep se gewig gedurende die laaste vyf maande van die intervensie verder toegeneem het. Die impak van die Handleiding word verder geïllustreer deur die feit dat die eerstejaar damesstudente in die eksperimentele groep wat aangedui het dat hul wel die Handleiding ekstensief gebruik het, 'n beduidend laer toename in gewig (LMI verandering gedurende studieperiode = 0.37 kg/m²) ondervind het as die studente in die eksperimentele groep wat aangedui het dat hul nie die Handleiding gebruik het nie (LMI verandering gedurende studieperiode = 0.89 kg/m²). Faktore wat moontlik gekoppel kan word aan die sukses verkry met die Handleiding is geïdentifiseer en sluit die volgende in: meer redelike gewigsdoelwitte; die gebruik van veilige gewigsverlies metodes soos 'n gebalanseerde dieet and fisieke aktiwiteit; verbetering van self-konsep; handhawing van fisieke aktiwiteitsvlakke, veral gedurende die eerste drie maande op universiteit; verbetering van algemene sielkundige welstand; verlaagde inname van voedsel van die "ander-" (sluit hoofsaaklik hoë vet, suiker gebasseerde voedsels soos oliebolle, koekies en tert in), drankies- en graanvoedselgroepe; en moontlik minder besorgdheid oor liggaamsvorm van die begin af. Faktore waarvoor geen verband met sukses met gewigshantering gevind is nie sluit die volgende in: liggaamsamestelling; persepsies van gewig; gewigsverliespogings; voedselinname uit die groente-, vrugte-, melk en kaas-, vleis, vis en hoender-, vette- en kitskosse-voedselgroepe; fisieke aktiwiteit gedurende die totale agtmaande periode; redes vir eet; eetgedrag en -houding; ontevredenheid met liggaamsdele; en besorgdheid oor liggaamsvorm. Dit word aanbeveel dat die implementasie van die Handleiding op die kampus van die Univérsiteit van Stellenbosch oorweeg word om gewigstoename van eerstejaar damesstudente te voorkom. Dit word ook aanbeveel dat die aanbevelings van die studente in die eksperimentele groep in hierdie verband, in ag geneem moet word.