Natural Course of Initially Metabolic Healthy Obese Individuals (Healthy Obesity)?

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)