Bariatric Surgery and Gut Microbiota Changes Over Time

The goal of this observational study is to learn how bariatric surgery affects gut bacteria and gut-related metabolic products over time in adults with obesity. The study includes adults aged 18 to 65 years who are undergoing Roux-en-Y gastric bypass (RYGB) surgery, as well as adults with obesity treated with diet alone and healthy normal-weight adults. The main questions it aims to answer are: How does bariatric surgery change the composition and diversity of gut bacteria over time? How are these changes related to weight loss and improvement of obesity-related health conditions? Researchers will compare people undergoing bariatric surgery with people with obesity treated with diet alone and with healthy normal-weight individuals to see if surgery leads to specific changes in gut bacteria and stool metabolites that are linked to better clinical outcomes. Participants will: Provide stool samples at scheduled time points over 12 months Provide blood samples and undergo routine clinical assessments Take part in follow-up visits to monitor weight, metabolic health, and gastrointestinal symptoms

NCT Number	NCT07381140
Lead Sponsor	Azienda Ospedaliera Specializzata in Gastroenterologia Saverio de Bellis
Conditions	Obese Patients, Obese Patients With Bariatric Surgery, Gut Microbiota, Healthy Participants
Enrollment	100 participants
Start Date	2026-04
Primary Completion	2027-04 (estimated)
Study Completion	2028-04 (estimated)
Updated on ClinicalTrials.gov	2026-02-05