Factors related with weight loss in a cohort of obese patients after gastric bypass

Introduction: Obesity is held as the 21^st Century epidemics. Multidisciplinary medical management has been insufficient and surgical techniques are more frequently used. Gastric bypass is considered the gold standard in bariatric surgery; however, some patients report low rates of weight loss, which leads to thinking about other conditioning factors. Objective: To establish the factors associated to weight loss in a cohort of obese patients submitted to gastric bypass. Methods: Analytical retrospective study. The study variable was weight loss, expressed as the percentage of excess body mass index lost (%EBMIL). A linear regression model of mixed effects was performed as well as a COX model of proportional risks. Results: 166 patients aged 19-69 years, most of them women (74.7%), were studied. The average baseline body mass index (BMI) was 46.9 ± 6.8 kg/m² and 46.3 ± 7.7 kg/m² for males and females, respectively. The multivariate analysis showed that for each 10.0 kg/m² in excess at the time of surgery, the PBMIEL decreased by 9.8% and that inadequate daily caloric intake decreased the PBMIEL by 4.0%. For each 10.0 kg/m² of baseline BMI, there was a 57.8% decrease in the likelihood of achieving a 50% weight loss. Conclusions: The patients with lower weight excess according to their BMI have a better response to bariatric surgery in terms of PBMIEL.