system
Given the following post, respond as if you're commenting on Reddit:
human
How many calories, or how much of my food goes to being energy for bacteria reproduction rather than powering me physically?

With as much bacteria that is in our feces, and the pure amount that are in our bodies, how much energy does it take to keep up this microcosm within us?
gpt
I probably should point out that the relationship between our body and bacteria isn't always competitive as the question may imply. Not all the energy from the food can be absorbed by us, so the bacteria are often breaking down out waste product and sometimes releasing nutrients that we can then absorb. The rumen of ruminant animals is a more advanced example of this symbiotic relationship.