Predictive Factors of Weight Loss 1 Year after Laparoscopic Gastric Bypass in Obese Patients

Background Substantial weight loss is achieved in majority of severely obese subjects undergoing laparoscopic gastric bypass (LGBP) but some fail to obtain expected results. Our aim was to identify preoperative factors that could influence weight loss (WL) 1 year after LGBP. Methods We studied the predictive value of clinical, biological, and dietary preoperative factors on weight loss in obese patients referred for LGBP. WL was assessed according to mean absolute weight loss (AWL) and mean percent excess weight loss (% EWL) 1 year after LGBP. Results One hundred twenty-three subjects were included (112 women, age 42 +/- 10 years; weight 127 +/- 23 kg; BMI 47 +/- 8 kg/m(2)). Mean AWL was 39.4 +/- 10.5 kg at 1 year, corresponding to a mean % EWL of 70.5 +/- 21.2%. AWL was positively correlated with initial weight, BMI, and energy intake and negatively with age, female sex, and treatment for hypertension and diabetes. % EWL was negatively correlated with initial weight, BMI, and positively correlated with triglycerides and ferritinemia. In multivariate analysis, % EWL was negatively correlated only with initial BMI (p < 0.001). AWL was positively correlated with initial BMI and male sex (both p < 0.001), and negatively correlated with protein intake (p = 0.039) and treatment for diabetes (p = 0.021), but not with biomarkers of diabetes and insulin resistance. Conclusion Initial BMI appears to be a strong determinant of individual WL, but predictive factors differ when WL was expressed as % EWL or AWL. The treatment of diabetes rather than diabetes itself appears to affect WL.