How Altered Gut-Brain-Axis Influences Food Choices: Part 1

Obesity is currently one of the most substantial health burdens. Due to the production of marked and sustained weight loss, bariatric surgery is an increasingly used therapeutic modality to combat obesity and its comorbidities. Surgical rearrangement of the gastrointestinal tract remarkably alters metabolism and hormones acting on neurological and hypothalamic signalling involved in food decision-making and eating behaviour. In this context, many patients who underwent bariatric surgery self-report changes in appetite, satiety and food preferences. Furthermore, new gut hormone-based (e.g. GLP1-receptor agonist or GLP-1-RA) pharmacotherapies which mimic the effect of bariatric surgery show impressive efficacy on weight reduction by modulation of food behaviour. However, the mechanisms of such functional changes, and how they relate to food decision-making remain unknown.

In this project, the investigators propose a novel approach to unravel the effect of obesity treatments (surgical and non-surgical) on the neural coding of nutritional attributes and its impact on dietary choices using a combination of brain imaging, computational modelling of food behaviour and assessment of eating and food purchase behaviour in daily life.

The overall aim of this project is to elucidate the neurobehavioural underpinnings of food behaviour among obese adults and how food behavior is altered by different obesity treatments.To this end, the study consists of an experimental setting combining neurobehavioural tasks, computational modelling and functional brain imaging.

The main objective of Part 1 of the BrainFood-project is to elucidate if neural coding and food behaviour differ between obese adults and lean adults. The investigators hypothesize that subjective neural processes of nutritional food attributes differ between the obese and control participants, showing an unhealthier pattern among obese participants.

To this aim, the outcomes will be compared between groups (surgery group and control group).

Eligibility Criteria:
Inclusion criteria (all participants):

* Female and male subjects aged 18 years or older
* Proficient German language skills (including written)

Inclusion criteria for Group 1 (pilot protocol):

* Class II-III obesity (BMI≥35kg/m2)
* Planned for bariatric surgery (Roux-en-Y gastric bypass)

Inclusion criteria for Group 1 (refined protocol):

* BMI≥30kg/m2 or BMI≥28kg/m2 with adiposity-related comorbidities (prediabetes, type 2 diabetes mellitus, hypertension, dyslipidemia)
* Referred for obesity treatment (surgical or non-surgical)

Inclusion criteria for Group 2 (pilot and refined protocols):

* Normal body weight (BMI 18.5-24.9kg/m2)
* Absence of evidence of any active or chronic disease as judged by the Clinical Investigator

Exclusion criteria:

* Incapacity to give informed consent
* Previous or current neurological or severe psychiatric illness
* Current or planned pregnancy or breastfeeding
* Claustrophobia
* MRI-contraindications (pacemaker/defibrillator, neurostimulator, drug pump, cochlear implant, heart valve/vascular clips, shunt valve)
* Pilot protocol only: Diabetes according to WHO (World Health Organization ) definition (Fasting plasma glucose ≥7.0mmol/l, random plasma glucose ≥11.1mmol/l, HbA1c ≥6.5%)