Assume the smoothies have the same nutrient profile as a regular diet. Like if you drank runny mashed potatoes and protein powder to simulate a normal food intake.
If you do poop because of the nutrients, is there a healthy diet at which waste products are no longer left in the intestine to turn into poop?
Drag has no intention of doing this, drag is just curious about the science.
Because its role is to aid in the voiding process. Much as part of the role of water is to serve as a carrier of urea out of the body, fiber’s job is to provide, bulk of a sort that’s easy on your intestines for the removal of waste. We could have evolved different dietary needs, but as fiber is plentiful in what we ate in the wild we adapted around it. Similar to how cats need external sources of taurine but we don’t.