This study focus on the cause of obesity and impacts of bariatric surgery on it.
Inclusion Criteria: 1. Body mass index ≥18 kg/m2 2. already received bariatric surgery or abdonimal surgery Exclusion Criteria: 1. acute stroke or acute myocardial infarction in 6 months 2. autoimmune disease 3. long-term use of non-steroidal anti-inflammatory drugs, corticosteroids and immunosuppressive drugs 4. pregnancy 5. consists with other endocrine diseases 6. acute infection in2 weeks 7. cancer 8. use of antibiotics in 3 months 9. chronic digestive inflammations 9