Excess Weight Loss after Roux-en-Y Gastric Bypass: The Trend and Associated Factors for weight loss

Background: Historically Roux-en-Y gastric bypass (RYGB) has been considered the gold standard of bariatric surgery. This procedure acts as a mixed restrictive and malabsorptive operation. Methods: This retrospective cohort study included 410 morbidly obese patients (BMI>40kg/m² or BMI>35kg/m² along with at least one major comorbidity) who underwent primary laparoscopic RYGB surgery from 2009 to 2015 by a single surgery team. The patients were aged 18 years and older with at least 12 months follow-up with alimentary and biliopancreatic limb length of 150 and 50cm respectively. Percent excess weight loss (%EWL), Percent excess BMI loss (%EBMIL) and comorbidity resolution were compared in short-term (12 months) and mid-term (12-60 months) follow-up. Results: The mean±SD age, weight, and BMI at surgery were 40.1±10.58 years, 123.32±19.88 kg, and 45.78±5.54 kg/m2, respectively, and 329 (80%) were female and 62 (15%) had T2DM. Mean±SD %EWL and %EBMIL was significantly higher in T2DM patients 9 months postoperatively and thereafter. Age at surgery, lower educational level, being single, and female patients had no significant effect on %EWL and %EBMIL during long-term follow-up. Patients with lower BMI at surgery (<50kg/m²) and non-diabetic patients had a significantly lower %EWL and %EBMIL over a short- and long-term follow-up (P<0.001). Conclusions: Bariatric surgery remains the most efficacious and durable weight loss treatment. However, a proportion of patients will experience unfavorable weight loss following bariatric surgery.