Excessive weight loss after bariatric surgery: a prediction model retrospective cohort study.

Bariatric surgery has been recognized as the most effective long-term treatment for morbid obesity. Despite the considerable positive results, adverse consequence can develop. Excessive Weight Loss (EXWL), a rare consequence of bariatric surgery, can lead to a broad adverse consequence. The aim of this study was determining of prevalence and the predicting model of EXWL in patient underwent bariatric surgery until 24 months after surgery. Data have been extracted from the National Obesity Surgery Database in obesity clinic of Iran University of Medical Sciences. The subjects of this retrospective cohort study were morbid obese individuals who underwent three various types of bariatric surgery [One Anastomosis Gastric Bypass (OAGB), Roux-en-Y Gastric Bypass (RYGB), or Sleeve Gastrectomy (SG)] in period of 24 months ago. EXWL has been defined as reaching to less than or equal to BMI 18.5 at any time until 24 months after surgery. SPSS was used in data analysis. Among 4214 subjects of this study, most excess weight loss after surgery has taken place in 18 months after surgery. 11.4% (n = 495) of patients experienced EXWL with highest percentage among OAGB patients (15.1%) at time of 24 months after surgery. The females (20.4% vs.9.9%) and younger persons (35.45 ± 10.25 vs. 39.06 ± 10.76) were more susceptible to EXWL. Patients with EXWL had significantly lower BMI (body mass index) (41.11 ± 4.51 vs. 46.73 ± 6.26) (Kg/m), and were less probable to had emotional eating. Visceral fat level, fat percentage, and BMI were the best predictor of EXWL (P value for all < 0.05). So that per level increase in visceral fat, decreases the probability of EXWL as 47% and 61% in SG and OAGB. Moreover, each unit lower BMI leads to 25% higher susceptibility to experience EXWL. Surgery should be adjusted in younger females with a lower BMI and healthy metabolic status who are more prone to EXWL. In such a way that minimize weight loss speed/value. It may be possible by selection of other surgery procedures, rather than OAGB, tighter follow-ups, and consultations of patients after surgery is emphasized for more EXWL vulnerable patients.