Introduction: The long-term success of non-surgical weight loss treatment in adults with obesity is limite by substantial relapse, and only a few evidence-based weight loss maintenance treatments exist. This clinical trial investigates the feasibility and efficacy of a social facilitation maintenance programme for weight loss maintenance, tailored to meet the needs of obese adults who have undergone a lifestyle weight loss intervention. Methods and analysis: In a single-centre, open feasibility trial, 72 adults currently or previously obese or overweight who have undergone a lifestyle weight loss intervention are centrally randomised to 4 months of social facilitation maintenance treatment or treatment as a usual control condition. In 16 outpatient group sessions, the social facilitation maintenance treatment, based on a socioecological model and on evidence supporting social facilitation as a key process in maintaining weight loss, focuses on promoting interpersonal relationships to build up a healthy lifestyle for long-term weight loss maintenance. Primary outcome is the amount of weight regain at 6-month follow-up, compared with pre-treatment weight, derived from measured body weight. Secondary outcomes address feasibility, including recruitment, attrition, assessment non-completion, compliance and patients’ programme evaluation; and in comparison with pre-weight loss maintenance, social and interpersonal functioning, eating behaviour and physical activity, psychological and physical symptoms, body composition and risk of comorbidity, and quality of life at post-treatment and follow-up assessments. Ethics and dissemination: The study was approved by the Ethical Committee at the University of Leipzig (165-13-15072013). The study results will be disseminated through peer-reviewed publications. Trial registration number: DRKS00005182

Objective: Analysis of short- and long-term effects of rapid response across three different treatments for binge-eating disorder (BED). Method: In a randomized clinical study comparing interpersonal psychotherapy (IPT), cognitive-behavioral guided self-help (CBTgsh), and behavioral weight loss (BWL) treatment in 205 adults meeting DSM-IV criteria for BED, the predictive value of rapid response, defined as ≥ 70% reduction in binge-eating by week four, was determined for remission from binge-eating and global eating disorder psychopathology at posttreatment, 6-, 12-, 18-, and 24-month follow-up. Results: Rapid responders in CBTgsh, but not in IPT or BWL, showed significantly greater rates of remission from binge-eating than non-rapid responders, which was sustained over the long term. Rapid and non-rapid responders in IPT and rapid responders in CBTgsh showed a greater remission from binge-eating than non-rapid responders in CBTgsh and BWL. Rapid responders in CBTgsh showed greater remission from binge-eating than rapid responders in BWL. Although rapid responders in all treatments had lower global eating disorder psychopathology than non-rapid responders in the short term, rapid responders in CBTgsh and IPT were more improved than those in BWL and non-rapid responders in each treatment. Rapid responders in BWL did not differ from non-rapid responders in CBTgsh and IPT. Conclusions: Rapid response is a treatment-specific positive prognostic indicator of sustained remission from binge-eating in CBTgsh. Regarding an evidence-based stepped care model, IPT, equally efficacious for rapid and non-rapid responders, could be investigated as a second-line treatment in case of non-rapid response to first-line CBTgsh.

Die vorliegende Dissertation setzt sich damit auseinander, wie das Zusammenspiel von essensbezogener Umwelt und Kognition Ernährungsentscheidungen beeinflusst. Im ersten Manuskript, “When Diets Last: Lower Cognitive Complexity Increases Diet Adherence” wird die Bedeutung der kognitiven Komplexität von Ernährungsregeln für das Einhalten einer Diät untersucht. Können Diäten scheitern, weil sie aus kognitiver Perspektive zu komplex sind, z.B. weil sich Diäthaltende nicht alle wichtigen Informationen merken oder verarbeiten können? 1136 Diäthaltende nahmen an einer längsschnittlichen Onlinestudie teil. Vorangegangenes Diätverhalten, Selbstwirksamkeit, Planung und wahrgenommene Regelschwierigkeit erhöhten das Risiko, die Diät vorzeitig aufzugeben, wobei Selbstwirksamkeit und wahrgenommene Regelschwierigkeit die einflussreichsten Faktoren waren. Im zweiten Manuskript „Meat Label Design: Effects on Stage Progression, Risk Perception, and Product Evaluation” wird der Einfluss gesundheitsrelevanter Information auf Labeln für Produktbewertung und Intention, Tierhaltung und Inhaltsstoffe von Lebensmitteln in die Kaufentscheidung einzubeziehen, untersucht. Es wurde betrachtet, wie Inhalt und Kontext (separate versus conjoint Darbietung) der Labelinformation die Bewertung von Fleischprodukten beeinflusst. Die Ergebnisse zeigen, dass sich bei einer conjoint im Gegensatz zur separaten Darbietung die Bewertung der Produkte umkehrt. Darüber hinaus hatten Personen, die zuvor nicht motiviert waren gesundheitsrelevante Aspekte in ihr Einkaufsverhalten einzubeziehen, nach Betrachten der Label eine höhere Intention diese zu berücksichtigen. Im dritten Manuskript, „Predicting Children’s Meal Preferences: How Much Do Parents Know?“, wurden Präferenzvorhersagen bezüglich der Essensentscheidungen Anderer erforscht. Es wurde untersucht, wie gut und mit Hilfe welcher Information Eltern die Mittagessenpräferenzen ihrer Kinder vorhersagen. Die Vorhersagegenauigkeit der Eltern entsprach der Stabilität der Essenspräferenzen ihrer Kinder, d.h. dass die Eltern so genau waren, wie möglich. Die Ergebnisse suggerieren, dass Eltern vor allem spezifisches Wissen über die Präferenzen ihrer Kinder und Projektion ihrer eigenen Vorlieben für die Vorhersagen nutzten. / This dissertation focuses on food-related decision making, in particular, how food related environments and cognition interact to determine people’s food choices. The first manuscript, “When Diets Last: Lower Cognitive Complexity Increases Diet Adherence,” investigates the role of the cognitive complexity in diet adherence. Can weight loss diets fail because they are too complicated from a cognitive point of view, meaning that dieters are not able to recall or process the diet rules? The impact of excessive cognitive demands on diet adherence were investigated with 1,136 dieters in a longitudinal online-questionnaire. We measured perceived rule complexity controlling for other factors known to influence adherence. Previous diet behavior, self-efficacy, planning and perceived rule complexity predicted an increased risk to quit the diet prematurely, with self-efficacy and diet complexity being the strongest factors. The second manuscript, “Meat Label Design: Effects on Stage Progression, Risk Perception, and Product Evaluation,” presents two studies which tested the impact of health-related meat labels on product evaluation and intention. Specifically, the studies examined how informational content and the context (separate vs. conjoint evaluation) in which labels are assessed influence the evaluation of meat products. The results showed that conjoint assessment of labels can lead to contrary product rankings compared to separate evaluations. Moreover, the results suggest that being exposed to food labels containing specific health-relevant information can increase motivation to consider health aspects in those consumers without previous intention to do so. The third manuscript, “Predicting Children’s Meal Preferences: How Much Do Parents Know?” investigated prediction behavior concerning other people’s food choices. In particular, it asked how accurately and what cues parents use to predict their children’s meal choices. Overall, parents’ prediction accuracy matched the stability of children’s meal choices, implying that accuracy was as high as can be expected. The results suggest parents were able to obtain high predictive accuracy by using specific knowledge about their child’s likes and projecting their own preferences.

Background: Overweight and obesity are significant public health concerns that are prevalent in younger age cohorts. Preventive or therapeutic interventions are difficult to implement and maintain over time. On the other hand, the majority of adolescents in the United States have a smartphone, representing a huge potential for innovative digitized interventions, such as weight loss programs delivered via smartphone applications. Although the number of available smartphone applications is increasing, evidence for their effectiveness in weight loss is insufficient. Therefore, the proposed study aims to assess the efficacy of a gamification-based smartphone application for weight loss in overweight and obese adolescents. The trial is designed to be a phase II, single-centre, two-arm, triple-blinded, randomized controlled trial (RCT) with a duration of 6 months. Method: The intervention consists of a smartphone application that provides both tracking and gamification elements, while the control arm consists of an identically designed application solely with tracking features of health information. The proposed trial will be conducted in an urban primary care clinic of an academic centre in the United States of America, with expertise in the management of overweight and obese adolescents. Eligible adolescents will be followed for 6 months. Changes in body mass index z score from baseline to 6 months will be the primary outcome. Secondary objectives will explore the effects of the gamification-based application on adherence, as well as anthropometric, metabolic and behavioural changes. A required sample size of 108 participants (54 participants per group) was calculated. Discussion: The benefits of the proposed study include mid-term effects in weight reduction for overweight and obese adolescents. The current proposal will contribute to fill a gap in the literature on the mid-term effects of gamification-based interventions to control weight in adolescents. This trial is a well-designed RCT that is in line with the Consolidated Standards of Reporting Trials statement.