The bulky fiber tends to slow gastric emptying, as with increased fat content seen in my paper "Gastric relaxation in response to a soup meal in healthy subjects. A study using a barostat in the proximal stomach. Undeland KA, Hausken T, Gilja OH, Ropert R, Galmiche JP, Berstad A. Scand J Gastroenterol. 1995 Nov;30(11):1069-76."