I have consistently struggled to keep weight off since I got a J Pouch. Weight gain or lack thereof I think ties in to your individual metabolism, level of exercise and diet. For me to be able to lose any weight I need to go on a borderline starvation diet. So I think it's highly individual and the best thing you can do is work with a registered dietician and/or personal trainer familiar with dietary issues of those with IBD to help fix any perceived weight gain or loss problem.