Clinical Research Directory

Inclusion Criteria: * Body mass index (BMI) ≥30 kg/m2 * Age 18-75 years * Signed informed consent * Ability to take part in a group-based nutrition advice * Adequate Finnish comprehension (since all advice and materials are in Finnish) Exclusion Criteria: * Unable to provide written consent * Attending another trial or having on-going dietary counseling at the same time * Pregnancy, breast feeding * Type I diabetes * Inflammatory disease * Liver disease other than NAFLD * Excess alcohol consumption (more than 20 g/day in females and more than 30 g/day in males, on average) * Dysmotility of upper GI-tract (e.g. gastroparesis) * Big hiatal hernia * History of a severe (anaphylactic) food allergy * Active, serious medical disease with likely life expectancy less than 5 years * Severe renal insufficiency (glomerular filtration rate \<30%) * Procedures that have changed the anatomy of GI-tract, including obesity surgery * Remarkable psychiatric disorders, dementia and other diseases or conditions that could affect to the study subject´s compliance to the study * Systemic antibacterial treatments * three months before the study or during the study * chronic or recurrent bacterial infection for which antimicrobial medications are repeatedly used * Contraindication for gastroscopy * Central anesthesia needed for gastroscopy * Medications for losing weight (bupropion/naltrexon, orlistat, liraglutide) * Intention to obesity surgery. Eligibility is evaluated by a doctor in each research unit.