Background/Aims: Higher body mass index (BMI) is associated with an increased risk of postoperative complications, but only a few studies have clarified the effect of higher BMI on perioperative outcomes in ulcerative colitis (UC). The purpose of this study was to evaluate the effect of higher BMI on patients undergoing surgery for UC. Methods: UC patients who underwent surgery between April 2012 and August 2015 were included. Higher BMI was defined as a BMI ≥25 kg/m2. Patients were classified as having a higher BMI or an unelevated BMI. We analyzed comparison characteristics, surgical outcomes, and pouch-related complications (PRC). Possible risk factors for PRC were also analyzed. Results: A total of 16 out of 165 (9.7%) patients had higher BMIs. The incidence of PRC in patients with higher BMIs was significantly higher than in those with unelevated BMIs. Male gender (OR 3.86, 95% CI 1.23–15.4, p = 0.02) and BMI ≥25 kg/m2 (OR 5.87, 95% CI 1.59–21.67, p < 0.01) were identified as independent risk factors for PRC. Conclusion: UC patients with higher BMIs had significantly higher incidences of PRC. Male gender and a higher BMI were identified as independent risk factors for PRC. The pouch operation as an initial surgery may be avoided in patients with higher BMIs to prevent PRC.