Addictive mechanisms in obesity: Is there a unique contribution of food addiction compared to binge eating disorder?

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Obesity is one of the major health problems in the Western World. At present, about 18% of the German population are diagnosed as obese as indicated by a body mass index (BMI) ≥ 30kg/m2. Unfortunately, the long-term efficacy of weight loss interventions is low. One way to enhance the efficacy may be to provide more tailored interventions for special subgroups of patients with obesity. The development of such interventions requires a better understanding of the psychological mechanisms that contribute to obesity. In this regard, two conditions related to obesity are particularly relevant: binge eating disorder (BED) and food addiction (FA). BED is the most common mental disorder reported in obesity and is characterized by frequent, recurrent episodes of binge eating during which the individual experiences a subjective loss of control over eating. Eating thereby seems to provide initially a relief from negative feelings, but results in shame and distress. The FA concept is based on the assumption that certain palatable foods (i.e. high in salt, fat, and refined carbohydrates) may trigger response patterns known from substance use disorders like craving, but also loss of control. In obese patients with BED, prevalence rates of FA of 57% are observed, suggesting that the constructs do not entirely overlap. However, there is at present a considerable lack of research differentiating obesity and FA and obesity and BED regarding underlying psychological processes. Against this background, the aim of this study is to investigate whether BED and FA are two distinct, yet overlapping, conditions regarding affective and cognitive psychological processes contributing to obesity. A mixed-methods between-subjects design with four groups (“obesity+FA+BED”, “obesity+FA“, obesity+BED, “obesity”; total N=360 participants) will be implemented. Diagnosis of BED and FA will be based on ICD-11-criteria, in the case of FA the criteria of substance use disorders will be adapted for food; all groups will be matched regarding age and gender (50% female). For all participants, inclusion criteria are BMI ≥30 kg/m2, and age ≥18 and ≤65 years. The study will comprise a single test-session lasting about three hours as well as a sixth-months follow-up (to explore the stability of the diagnoses). Experimental tasks with food-related and neutral stimuli will be administered and questionnaires on, for example, difficulties of emotion regulation and experiences of gratification and compensation from food. We expect that a diagnosis of FA will be associated with more severe cue-reactivity, a more pronounced approach bias towards food, deficits regarding delay discounting and higher gratification from food, while we expect that BED will be associated with higher deficits of emotion regulation and higher feelings of compensation from food. We expect that obese patients with FA and BED will show the greatest impairment of food-related inhibitory control compared to all other groups.