Bariatric SurgeryObesity, MorbidGastric BypassGastroplastyWeight LossBiliopancreatic DiversionObesityBariatric MedicineJejunoileal BypassHyperoxaluriaPostoperative ComplicationsAvitaminosisPreoperative PeriodAnastomosis, Roux-en-YLaparoscopyBody Mass IndexTreatment OutcomePostoperative PeriodBariatricsGastrectomyInformed Consent By MinorsPostoperative CareGastric FistulaTooth WearProspective StudiesDiabetes Mellitus, Type 2Preoperative CareMalabsorption SyndromesFollow-Up StudiesAnti-Obesity AgentsRetrospective StudiesPerioperative PeriodGlucagon-Like Peptide 1Patient SelectionPeptide YYGastrointestinal HormonesGastric BalloonRisk FactorsComorbidityReoperationSecondary Care