Dissertation Docteur De L'université Du Luxembourg
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PhD-FLSHASE-2015-40 The Faculty of Language and Literature, Humanities, Arts and Education DISSERTATION Defense held on 18/12/2015 in Luxembourg to obtain the degree of DOCTEUR DE L’UNIVERSITÉ DU LUXEMBOURG EN PSYCHOLOGIE by Zoé van Dyck Born on 21 February 1986 in Luxembourg (Luxembourg) THE ROLE OF EXTERNAL AND INTERNAL STIMULI IN THE REGULATION OF EATING BEHAVIOUR Dissertation defense committee Prof. Dr. Claus Vögele, dissertation supervisor Professor, University of Luxembourg Prof. Dr. Dieter Ferring, Chairman Professor, University of Luxembourg Dr. André Schulz, Vice Chairman University of Luxembourg Prof. Dr. Simone Munsch Professor, University of Fribourg Prof. Dr. Jens Blechert Professor, University of Salzburg Dissertation Defence Committee Prof. Dr. Claus Vögele, University of Luxembourg (Supervisor) Prof. Dr. Dieter Ferring, University of Luxembourg (Chair) Dr. André Schulz, University of Luxembourg Prof. Dr. Simone Munsch, University of Fribourg, Switzerland Prof. Dr. Jens Blechert, University of Salzburg, Austria 1 2 Curiosity is the key to problem solving. (Galileo Galilei, 1564-1642) 3 4 Acknowledgements I would like to thank and acknowledge everyone who helped and supported me and who contributed to my research. You all made my PhD years an exciting, valuable and great experience. First and foremost I would like to thank my supervisor, Claus Vögele, for all your support and for believing in my work as a researcher. Thank you for trusting in my autonomy, and at the same time always being there when I needed your help, advice, and opinion. I could not have imagined a better way of scientific guidance. I also highly appreciate the support and advice offered by Jens Blechert. Thank you for your great ideas and suggestions in the planning phase and your valuable contribution and feedback during the writing process. I have learned a lot from you. I owe special thanks to Dieter Ferring; this doctoral project was possible on account of your support and approval. My appreciation also goes to Simone Munsch, for having agreed to be part of my dissertation defence committee and taking up the long journey to Luxembourg. I heartily thank my Scientific Advisors: Beate Herbert for the inspiring discussions and valuable contribution and feedback during the planning and writing of my studies, and André Schulz for the scientific and moral support and important input to this project – I have learned a great deal from you. I would also like to thank everyone at the INSIDE Research Unit and especially the Self-Regulation and Health team. Apart from the more formal professional interactions, I will mostly remember the time we have spent together informally. A very special thanks to Annika and Silke, who have always been there to support me both professionally and personally. You are not only great colleagues but also wonderful friends. Anne and Claudia, my dear former colleagues: Our time together in Fribourg was short, but a long friendship results from it. You understand like no one else the ups and downs of doing a PhD. Thank you for all your support and the great weekends in Leipzig, Gerlafingen, and Luxembourg. I am already looking 5 forward to the next one. I also want to thank Alan Murdock and his wonderful wife Elke. Alan, thank you for proof-reading all of my boring (now you can admit it) manuscripts. If one day you should write a thesis in Luxembourgish, don’t hesitate to ask for my help. A big thank you for all the students who helped me in data collection and supported me managing this mammoth project (Sonja, Jessica, Gillian, Annabel, Marie, Mareike, Elise, Constanze, and many more). This work would not have been possible without your outstanding help and commitment. I would also like to thank all those who participated in my studies and endured the up to eight hours testing for the sake of research. It was a wonderful experience meeting you all and without you this thesis would not have been possible! I want to thank my family and friends for their open ears and minds and their patience with me during these work-loaded last four years. E ganz groussen Merci geet virun allem un meng Elteren, Pia an Marc, fir hier onersetzbar an inconditionnel Ënnerstëtzung mäin Liewen laang. Et ass en wonnerbart Gefill ze wëssen, dass ech ëmmer eng Platz bei iech hunn an heem kommen kann, egal wei fuerchtbar schrecklech grad alles ass. Menger Schwëster, dem Tammy, villmools Merci dass du ëmmer en oppent Ouer fir mech has (an hues) an mech op aner Gedanken bruecht hues, virun allem wann ‘s de mat engem Owesiessen an enger Fläsch Wäin laanscht komm bass fir mech vum Computer ewech ze zeien. Nanni, Merci fir déi flott Freideg Mëttesstonnen. Ech hoffen, dass mir déi Traditioun nach laang wäerten weider féieren. Sarah, Géraldine G. an Géraldine B., mir ginn lo schonn säit esou villen Joeren zesummen duerch all Déiften a Héichten an ech kann mech wierklech glécklech schätzen esou Frëndinnen un menger Säit ze hunn. Dir hutt mir virun allem an deenen leschten ustrengenden Wochen vill Kraaft ginn. Ech war sécher net ëmmer einfach ze erdroen, hunn mech seelen 6 gemellt, ma trotzdem hutt dir mech während der ganzer Zäit bedengungslos ënnerstëtz. Dir sidd super! Mengem Matbewunner dem Sébastien och e groussen Merci fir déi super Zäit. Dofir, dass du mech moies mat Orangejus versuergt hues an ëmmer en oppent Ouer has wann ech mol erëm soueren misst. Aber der größte Dank gilt Christian, der mich die ganzen Jahre hindurch sowohl privat als auch fachlich unterstützt hat wie kein anderer. Ich weiß, dass es auch für dich nicht immer einfach war und trotzdem warst du immer da wenn ich dich brauchte. Du bist der beste Partner, Freund und Mitarbeiter den man sich vorstellen kann. Danke! 7 Abstract Obesity and eating disorders are growing public health problems that affect many individuals world-wide. Research suggests that this obesity epidemic is attributable to our obesogenic environment, where appealing but energy-dense foods are everywhere and anytime available. Yet, within the same environment, there is considerable variation between individuals regarding their susceptibility to overeat and gain weight. It has been argued that a selective attention to food could be an important factor contributing to susceptibility for overeating and binge eating. Another line of research suggests that disordered eating behaviours are characterised by altered responsivity to internal hunger and satiety signals. The present project was designed to investigate these ‘external’ and ‘internal’ stimuli and their role in regulating eating behaviour. In Study 1, we experimentally investigated the causal role of attentional bias for eating behaviours in a nonclinical sample. Results showed a sustained effect of attentional training on attentional bias and food choice, but not on craving. Moreover, training effects differed according to whether or not participants were aware of the experimental contingencies. In Study 2, we translated and validated a German version of the Intuitive Eating Scale (IES-2) and applied it to a sample of eating disordered women. The German IES-2 yielded good psychometric properties and women with an eating disorder displayed significantly lower intuitive eating scores compared to healthy participants. Study 3 described the development and evaluation of a standardised drink test to measure gastric interoception. Results showed that this two-step Water Load Test (WLT-II) is a simple and reliable test that distinguishes well between sensations of comfortable satiation and unpleasant fullness. Furthermore, the volume of water ingested until satiation was found to be related to bulimic symptoms. In Study 4, the WLT-II was applied to a sample of patients with bulimia nervosa (BN) or binge-eating disorder (BED). Eating disordered patients displayed delayed satiation compared to healthy control participants. In addition, gastric myoelectrical activity 8 was measured by electrogastrography (EGG) before and after water ingestion. BN and BED patients had increased gastric dysrhythmia and percentage of normogastria was negatively related to frequency of binge eating. We conclude that enhanced attentional processing of food stimuli and a dysfunctional perceptual processing of physiological mechanisms signalling meal termination are key factors that may contribute to overeating or binge eating. 9 Contents 1. INTRODUCTION ............................................................................................................ 12 1.1. Obesity and binge eating ........................................................................................... 14 1.1.1. Overweight and obesity ...................................................................................... 14 1.1.2. Bulimia Nervosa and Binge-Eating Disorder ..................................................... 15 1.2. External stimuli: Food cue reactivity ......................................................................... 24 1.2.1. The ‘toxic’ food environment ............................................................................ 24 1.2.2. Food cue reactivity ............................................................................................. 25 1.2.3. Eating and addiction ........................................................................................... 26 1.2.4. Attentional bias for food cues ............................................................................ 28 1.3. Internal stimuli: Visceroception and the perception of hunger and satiety ..............