In Western culture, we tend to eat three large meals a day (except perhaps for those who skip breakfast). Most people tend not to eat snacks between meals, but snacking could be a way to combat a lack of appetite. Eating small meals several times a day could help people with IBD to take in the calories they need to maintain a healthy weight. A smaller meal may also help in avoiding bloating and discomfort that may occur after eating a larger meal.
Brown AC, Rampertab SD, Mullin GE. "Existing dietary guidelines for Crohn's disease and ulcerative colitis." Expert Rev Gastroenterol Hepatol. 2011 Jun;5:411-425.