"Fecal bulk" refers to the amount and consistency of stool (feces) in the digestive system. It indicates how well-formed and full the solid waste is before being eliminated from the body. Full definition
Compared to the low fiber control, the wheat bran supple - ment increased fecal bulk by 96 Â ± 14 g / d (p < 0.001) and the mean for both resistant starches was 22 Â ± 8 g / d greater (p = 0.013). (nap.edu)