"In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return."Genesis 3:19 KJV
I teach high school biology. I happen to love teaching, and I enjoy learning how things work, but many of my lambs come to high school with some deep misconceptions that skew their world view.
It's mid-January, a busy time of year, but I need to take a few moments to talk to my colleagues at the elementary school level.
Psssst...you, yeah, you....come a little closer.....poop is not digested food.
The food that gets chopped into bits tiny enough to enter cells either ends up as part of you or exits as part of your breath (CO2) or your water.
When you diet, most of the you you lose is lost as carbon dioxide, bits of you lost with every exhaled breath. Some is lost as water, some as urea, but most of it gets cast off with each breath. I once lost 60 pounds, breath by breath by breath.
Why does this matter?
It gets the knee-high crowd thinking of mass ("stuff") as something other than solids. It complicates the whole food to poop business.
Trees are massive hunks of stuff made mostly of carbon dioxide drawn in through tiny holes in their leaves. We're massive hunks of stuff made from the stuff we eat, stuff mostly put together by plants.
Carbon dioxide to food to carbon dioxide again.
Thou art carbon dioxide, and to carbon dioxide shalt thou return.
OK, bile comes from RBC's, which were once food--but this does little more than give poop its lovely colors.