The primary aim of this study is to investigate the nasal environment in obese and lean individuals.

Inclusion Criteria:

N=50 adult male and female patients with obesity will be included in this study.

Inclusion criteria:

Inclusion criteria:

• Age 18-55 years
• Written informed consent
• BMI > 30 kg/m2

N=50 adult lean patients age- and sex-matched to the group of obese patients will be included in this study.

Inclusion criteria:

• Age 18-55 years
• Written informed consent
• BMI 18-25 kg/m2

N=50 adult male and female patients with obesity with scheduled bariatric will be included in this study

Inclusion criteria:

• Age 18-55 years
• Written informed consent
• BMI > 35 kg/m2

Exclusion Criteria:

• Smoking
• Chronic or acute sinusitis
• Surgical intervention of the nasal cavity or the paranasal sinus
• Use of antibiotics within the last 31 days18
• Current illicit drug abuse including daily marijuana or CBD consumption (≤ 24 g of alcohol per day allowed)
• Any kind of severe chronic disease (e.g. severe heart failure, active cancer disease)
• Use of any kind of decongestant more than twice a week
• Use of cortisone-containing nasal spray within the last 3 months
• Acute allergic rhinitis
• History of neurodegenerative diseases
• History of severe head trauma
• Severe renal impairment (e.g. estimated glomerular filtration rate <30 ml/min/m2)

Male and female participants between the age of 18-55. 50 participants with obesity, 50 lean participants (age- and sex-matched), 50 patients with schedueled bariatric surgery