Why ulcerative colits isn't stopping my growth at the gym?

??: Do not understand your question. In general UC and Crohn's will not hinder growth as long as you are not taking steroids long term. It is the steroids that cause problems and in the setting of Crohn's, malnutrition can sometimes be a problem.

Your growth : At the gym shouldn't be limited by your ulcerative colitis. In fact there are famous bodybuilders with ulcerative colitis. Just remember that prednisone is not an anabolic steroid, so it will not contribute to your growth at the gym.