The main goal of this study is to gain a thorough understanding, which specific factors drive the unhealthy sequelae of obesity. Therefore, the investigators want to understand:

1. What distinguishes obese persons without metabolic diseases from those with medical diseases in a cross-sectional comparison?
2. Which factors drive the conversions from metabolically healthy obesity into a metabolically unhealthy obesity in a longitudinal approach?

The hypothesis is, that changes in the molecular regulation of adipose tissue as well as in adipose tissue cellular composition are responsible for the development of a rather metabolic healthy or unhealthy phenotype. Knowledge of these factors will be used to generate new diagnostic concepts for personalized risk prediction and will furthermore serve as the basis to develop novel strategies to target adipose tissue to improve metabolic health.

Inclusion Criteria:

• Signed Informed Consent Form
• Age between 18 and 60 years
• BMI 30-50 kg/m2
• Knowledge of German, which requires sufficient written and allow oral patient education

Inclusion criteria for initially healthy group

• Blood pressure < 140/90 mmHg

• Normal glucose metabolism

  • HbA1c < 6.5 %
  • Fasting Glucose < 7.0 mmol/l

• Normal lipid metabolism

  o LDL-cholesterol < 5.0 mmol/l

• ≤ 2 of the following metabolic syndrome criteria combined (excluding waist circumference)

• TG > 1.7 mmol/l

• HDL-cholesterol > 1.0 mmol/l (male) / > 1.3 mmol/l (female)

• Fasting glucose ≥ 5.6 mmol/l

• BP ≥ 130/85 mmHg

Exclusion Criteria:

• Pregnancy
• Medication and / or pathologies that prevent a safe execution of the fat tissue biopsies
• History of or planned bariatric operation
• Medical conditions that prevent examinations and testing (e.g. symptomatic cardiovascular diseases)
• Active Malignant tumor (<2a remission)

obese participants