system
Given the following post, respond as if you're commenting on Reddit:
human
Does fiber simply speed up our digestive system, or do our bodies want to expel fiber quickly?
gpt
Fiber acts as a bulking agent, and as mentioned by HonorAmongSteves, it carries water, creating a rather substantial mass that moves through one's digestive tract. Peristaltic movements by the colon and eventually defecation are stimulated by stretch receptors present in the wall of the colon. Due to the increased bulk in the colon, stretch receptors are activated, passage is expedited, leading to a faster mouth to anus transit.