Inclusion Criteria:  General Inclusion Criteria:  Aged between 18 and 60 years; Ability to understand and provide informed consent (in French); Ability and willingness to meet the required schedule and study procedures; Group-Specific Inclusion Criteria: Control Group  Inclusion criteria for the participants from the Control group are:  Presence of Gastroesophageal Reflux Disease symptoms or gastric discomfort. BMI [19kg/m² < BMI <25 kg/m²] Match age and sex to the patients from the Ob and ObD groups.  Only patients with normal glucose tolerance (NGT), glucose tolerance (IGT) and/or fasting glucose (IFG) and an HbA1c < 6.5 % will be included in this group.  Ob Group  Inclusion criteria for the participants from Ob and ObD groups are:  ● Candidate for bariatric surgery and meet the HAS criteria (Haute Autorité de Santé, 2009) :  IMC ≥ 40 kg/m² without comorbidities Or IMC≥ 35 kg/m² with at least one obesity-related comorbidity (i.e.: Hypertension, Dyslipidemia, Obstructive Sleep Apnea, Joints Disease, non-alcoholic steatohepatitis, excluding T2D) Weight stable for at least 2 months No treatment for metabolic health complications, no previous obesity surgery, no obesity treatment drug.  No monogenic form of obesity (Hebebrand et al., 2017)  ObD Group  Inclusion criteria for the participants from ObD groups are:  Candidate for bariatric surgery with T2D At least one obesity-related comorbidity including T2D Fasting plasma glucose (FPG) ≥7 mM (=1.26g/l) or Participants with HbA1c ≥ 6.5% (48 mmol/mol) All stages of albuminuria  Exclusion Criteria:  General Non-inclusion Criteria:  Treatment for the previous 12 week that could  alter gastrointestinal motor function (e.g. opioids, prokinetics, anticholinergics, laxatives), acidity (PPI, H2RA) microbial population (e.g.: antibiotics, probiotics) immunosuppressants (eg: calcineurin inhibitors, corticosteroids, biological agents, etc.). use of weight-loss drug or dietary intervention aiming to lose weight;  Altered anatomy of the esophagus, stomach, small or large intestine due to prior gastrointestinal surgery (exceptions include appendectomy or cholecystectomy more than 3 months prior to enrollment) or other reasons;  Any abdominal or pelvic surgery within the past 3 months; Diverticulitis, diverticular stricture, or other intestinal strictures. Intestinal resection of the gastrointestinal tract Previous history of gastric bezoar or gastroparesis Acute or chronic inflammatory bowel disease or infections diseases (i.e.: VHC, VHB, VIH, etc.) Abdominal or pelvic radiotherapy or abdominal cancer Colorectal cancer, either known or not Dysphagia, eosinophilic esophagitis, esophageal stricture, or other swallowing disorder Organ Transplantation and patients on Immunosuppressive Therapy Severe kidney failure and/or patients on dialysis therapy (serum creatinine > 150 μmol/l or eGFR < 60 ml/min per 1.73 m2 body surface area) CVD, endocrine, renal or other chronic disease likely to affect motility. Colon cleansing preparation during the last 1 month No < 3 bowel movements per week Females of childbearing age who do not practice birth control and/or are pregnant or lactating Participants non-affiliated to the French national health scheme Participants who are already included in a clinical study which implies testing any pharmaceutical drug. Participants who do not understand the research procedures those who are institutionalized, or who unable to give informed consent Participants placed under legal protection Patients with drug addiction Antibiotherapy 3 months preceding the endoscopy Weight variation (diminution or increase) > 5kg in the last 3 months Specific non-inclusion Criteria  Ob and ObT2D Group  Usual contraindication for bariatric surgery;