**3.5 Inflammatory bowel disease (IBD)**

Historically, IBD patients were unlikely to be overweight or obese due to the malabsorption and catabolic disease state; however, the increasing rates of obesity along with enhanced therapeutics have now resulted in higher incidence of obese patients. The prevalence of obesity and severe obesity among IBD patients is about 20–30% and 2–5%, respectively [69]. LSG is safer compared with RYGB for IBD patients as immunosuppressant drugs might place IBD patients at higher risk of surgical complications. The underlying nutritional deficiencies in IBD patients may also increase susceptibility to micronutrient deficiencies after BS. Moreover, IBD could increase the conversion rate of laparoscopic to open surgeries [70]. Despite these concerns, studies have found that LSG has favorable outcomes in patients with IBD. For example, one study showed that among patients with Crohn's disease (CD) or ulcerative colitis (UC) who underwent RYGB (n= 19) and LSG (n= 35), both operations led to significant WL at 1 year [71]. Additionally, a sizable proportion of patients experienced improvements in IBD after RYGB and LSG [71]. There were no significant differences in the proportion of patients with UC who had improved (27% vs 8%), unchanged (64% vs 92%), or worse (9% vs 0%) IBD medication requirements, respectively [71]. Similar analysis among patients with CD showed no significant differences in the proportion of patients who had improved (37.5% vs 44%) or unchanged (25% vs 52%) IBD-medication requirements after RYGB and LSG, respectively. However, there was a significant difference in the proportion of patients who had worsened CD after RYGB compared with LSG (37.5% vs 4%, p = 0.016) [71]. In terms of complications, a metanalysis (10 studies) favored LSG over RYGB for early (<30 days) complications (LSG 14.9% vs RYGB 28.9%) and late (>30 days) complications (LSG 15.0% vs RYGB 26.8%) [70].
