Olfactory Odour Stimulation for Metabolism Control

Inclusion Criteria: * Age 18-70 years * Obesity (BMI ≥35 kg/m2) * Written informed consent * Normosmia (defined by sniffin Sticks test) Exclusion Criteria: * Known allergy to D-Limonene, citrus fruits, citrus flavours, SLVO * Regular smoking * Current illicit drug abuse including daily marijuana and cannabidiol (CBD) consumption (alcohol ≤2 drinks per day allowed) * Diabetes mellitus * Pre-Treatment with insulin sensitizing drugs including GLP-1 analogues * 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 * Acute upper respiratory tract infection * Uncontrolled dysthyroidism * Uncontrolled hypertension * Regular use of psychopharmaceutic drugs * Patient aims to start a new diet or exercise program during the study * Bariatric surgery * Pregnancy/Lactation * Symptoms of menopause * Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. * Participation in an interventional study within the last 3 months