Gender-Specific Weight and Body Composition Changes Following Roux-en-Y Gastric Bypass

Purpose: Changes in weight and body composition, and rates of parameter change within and between genders, were studied preoperatively and serially within the first postoperative year after Roux-en-Y Gastric Bypass (RYGB). Analysis included 146 patients (115 women and 31 men) who were compliant with all visits. Preoperative variables included weight (Wt), body mass index (BMI), and body composition evaluated using ElectroLipoGraphy. Postoperatively, changes in those variables, percent excess weight loss (%EWL), and %Lean Lost (lean mass lost/weight loss) were evaluated. Main Findings: Both genders demonstrated significantly favorable Wt, BMI, %EWL, and body composition changes. %Lean Lost was the only parameter that did not significantly change for both genders. Between-gender changes were significant for all variables except BMI, %EWL, fat mass, and lean mass lost. No slopes of changes differed significantly between genders. Principal Conclusions: RYGB effectively accomplishes favorable weight and body compositions for both genders during the first postoperative year. Findings were used to suggest gender-specific, evidence-based clinical practice guidelines to assess body composition changes. Monitoring changes can help both genders achieve a healthier body weight primarily from fat mass loss while sparing lean mass.