It is an example of a withdrawal reflex.
The event order should be:
1. Ingesting food, the small bowel filled with food solutes and become hypertonic. It will attract water from the blood which is hypotonic
2. Food digested, some of it absorbed. The osmotic pressure inside bowel will be reduced.
3. All food is absorbed, the osmotic pressure reduced significantly makes it hypotonic. The blood attracts water as it is hypertonic. This will increase the blood volume
Answer:
In my personal opinion, yes, this is a pretty typical behavior of human beings. I'd say it's naturalistic in a way.
