The rate of diagnoses has increased for both obesity and IBD, and some research suggests that obesity may play a part in the development of IBD. About 15-40% of patients with IBD are obese, which is defined as having a body mass index (BMI) of 30 or higher. However, there has been little research on how obesity might affect outcomes in patients with IBD. In this study of nearly 7300 patients with IBD, we found that about one in 5 patients with IBD were obese. Obese patients were more likely to have active symptoms related to IBD, as compared to patients with normal BMI. Over a period of 12-18 months, we obs erved that obese patients with active disease were significantly less likely to achieve remission. Similarly, among patients in remission at baseline, obese patients were 2-3 times more likely to relapse on follow-up, as compared to patients with normal BMI. Obese patients with IBD were more likely to have anxiety, depression, fatigue, and experience pain. They were also less satisfied with their ability to participate in social roles. These effects were seen in patients with both ulcerative colitis and Crohn's disease. Future studies to find out whether treating obesity may improve outcomes in patients with IBD are needed.