RESUMEN
Background: The effect of bariatric surgery on weight loss (WL) of patients with severe obesity is an established finding. However, some studies have shown that other factors such as demographic characteristics can also be involved in the extent of success and relapse of obesity. Thus, this study was performed to determine the association of demographic characteristics with the rate of weight loss and changes in nutritional factors one year after one anastomosis gastric bypass (OAGB). Materials and Methods: In this cross-sectional study, 121 patients undergoing OAGB were investigated. Patients' body mass index (BMI), nutritional factors (including levels of albumin, vitamin D3, and serum ferritin), and demographic characteristics were measured one year after the surgery. Results: The BMI one year after surgery was significantly lower than before surgery (47.12 ± 5.08 kg/m2 vs. 29.42 ± 3.86 kg/m2; P value <0.001). WL was 37.37 ± 6.70%. In addition, the serum level of vitamin D3 one year after surgery with the mean of 44.54 ± 17.25 was significantly higher than its level before surgery with the mean of 38.13 ± 14.42 (P value <0.001). WL in less than 50 years old and married patients was significantly higher than WL in over 50 years old and single patients (P value <0.05). Moreover, the decrease in serum ferritin level with the mean of 1.90 ± 0.56 ng/ml in women was significantly higher than its decrease with the mean of 3.02 ± 0.94 ng/ml in men (P value = 0.003). Conclusion: Some demographic characteristics such as age, gender, and marital status seem to affect the rate of weight loss or ferritin level one year after OAGB.