Obesity, MorbidObesityGastroplastyGastric BypassBiliopancreatic DiversionBariatric SurgeryWeight LossAnastomosis, Roux-en-YBody Mass IndexLaparoscopyJejunoileal BypassAvitaminosisObesity, AbdominalSurgical StaplersPostoperative ComplicationsJejunumPediatric ObesityStomachBody WeightGastrectomyLeptinElephantiasisIleumVitamin B DeficiencyAdipose TissueInsulin ResistancePrader-Willi SyndromeRisk FactorsTreatment OutcomeOverweightPrevalenceDiabetes Mellitus, Type 2Fatty LiverFollow-Up StudiesReceptors, LeptinMalabsorption SyndromesEatingInsulinBlood GlucoseComorbidityMetabolic Syndrome XProspective StudiesMethodsTime FactorsPostoperative CareDiabetes MellitusDigestive System Surgical ProceduresUnited StatesRetrospective StudiesAnti-Obesity AgentsAdiposityDietCohort StudiesWaist CircumferenceWeight GainCross-Sectional StudiesEnergy MetabolismSurgical Procedures, Minimally Invasive