How does the insoluble fiber component of acorn squash contribute to maintaining digestive regularity?

It acts like a scrub brush, adding bulk to stool and promoting regular bowel movements.

The text delineates the functional difference between soluble and insoluble fiber found within acorn squash. Insoluble fiber, unlike its soluble counterpart, does not dissolve when exposed to water in the digestive tract. Instead, it retains its structure and passes through largely unchanged, serving a mechanical purpose. This action is described analogously as acting like a 'scrub brush' within the digestive tract. By absorbing water and adding physical mass or bulk to the contents of the intestines, insoluble fiber helps ensure that peristaltic action moves waste material efficiently, which is the mechanism that promotes regular bowel movements and helps prevent the development of constipation.