OLFactory Odour Stimulation and FOOD Preferences

Inclusion Criteria: * Age 18-60 years * Written informed consent * BMI ≥30 kg/m2 * Normosmia (as defined by Sniffin' Sticks Test) Exclusion Criteria: * Known allergy to olfactory stimulation substance, citrus fruits, citrus flavours, citrus food products * Lactose-intolerance, celiac disease or non-celiac wheat sensitivity * Diet other than omnivore or vegetarian * Eating disorder (now or in the past) * Dysphagia * Acute disease affecting food intake * Acute upper respiratory tract infection, acute or chronic sinusitis * Severe visual impairment (vision \<10%) * Surgical intervention of the nasal cavity or the paranasal sinus * Current illicit drug abuse including daily marijuana and CBD (Cannabidiol) consumption (alcohol ≤2 drinks per day allowed) * Any kind of severe chronic disease (e.g. severe heart failure, active cancer disease) * Type 1 and 2 diabetes mellitus * Treatment with insulin-sensitizing drugs within the last 3 months * Treatment with Glucagon-like Peptide 1 (GLP1)-analoga * History of neurodegenerative diseases, severe head trauma * Severe renal impairment (e.g. estimated glomerular filtration rate \<30 ml/min/m2) * Known liver cirrhosis or other severe liver impairment * Use of any kind of decongestant more than twice a week * Uncontrolled dysthyroidism * Uncontrolled hypertension * Regular use of psychopharmaceutic drugs * Study participants aims to start a new diet or exercise program during the study * Bariatric surgery * Pregnancy/Lactation * Inabilit…