Patients with steady medication during the last 3 months. A diabetes mellitus must not be decompensated (HbA1c <6.5%). Patients with advanced fibrosis - defined about the non-invasive Fibroscan-procedure (Fibroscan >13 kPa) - will not be included.  Complete inclusion criteria:  Age between 18 and 75 years Body Mass Index (BMI) > 25 kg/m2 Grade 3 steatosis evaluated by with CAP ≥ 300 dB/m and exclusion of known causes of liver steatosis Liver elastography < 13 kPa Capability to understand the study and the individual consequences of participation Signed and dated declaration of agreement in the forefront of the study  Complete exclusion criteria:  Liver cirrhosis Hepatocellular carcinoma or non-curative treated carcinoma Alcohol consumption >20g (female) und >30 g (male)/day Other causes of chronic liver disease (HBV, HCV, HDV, HEV, HIV), autoimmune diseases or chronic cholestatic liver disease, hereditary haemochromatosis, Wilson disease, α-1-Antitrypsin deficiency Medications which cause liver disease or secondary NAFLD (e. g. Tamoxifen, systemic Corticosteroids, Methotrexate, Tetracycline, Estrogens, Valproic acid) Changes in body weight > 5% in the last 6 months Statins and/ or other fat-reducer medications if not taken in steady dosage during at least 4 weeks Uncontrolled diabetes type 2 defined as HbA1c value > 9.0% or insulin depending type 2 diabetes Pregnancy Immunologic or inflammatory disease (e. h. systemic lupus erythematodes) Patients after organ transplantations Missing or lacking consent capability