Purpose: To analyze the outcomes of patients in whom we performed a SG depending on the calibrating bougie.Methods: Retrospective review of patients who underwent SG. Baseline characteristics were analyzed, and outcomes compared between groups. In order to identify the contribution of each predictor in the %EWL, a linear regression univariate and multivariate model was constructed.Results: 168 LSG were performed (120 women), mean age 42.9 years and BMI 51.1. Mortality rate of 0.3% and morbidity rate of 4.7%. No differences in terms of complications between both groups (5.8% vs 3.2%, p=0.735), while %EWL was statistically superior in the 40fr group (67.4±17.9 vs 58.1±15.6 at 24 months, p=0.012). Age, larger bougie size and arthropathy influenced negatively on the %EWL. In the multivariate analysis, the introduction of the variable "surgeon" produced a reduction of the effect of the bougie size in weight loss at 24 months (mean difference between groups is 7.5; 95% CI (3.4 -18.3); p=0.173).Conclusions: There are differences regarding %EWL in the medium term favoring the use of a 40Fr bougie against the 58 Fr one, with no differences in terms of complications. As well as the bougie, the surgeon plays an important role in the %EWL.