The question, “If I weigh 99 pounds, and I eat one pound of nachos, am I 1 percent nacho?” doesn’t seem that complicated, right? Wrong. People have always told you “you are what you eat,” but that isn’t quite the case.
SciShow host Hank explains in the video above that the answer, actually, turns out to be “super complicated.” Hank answers a few smaller questions to answer the larger question: if you eat nachos are you nachos?
Question #1: “After my digestive system dissolves them into a mushy, acidic goo? Are they nachos then?”
Hank says, “If you took what was in my stomach an hour after I ate nachos and put it on a plate, zero people out of seven billion would call that nachos. However, the atoms and molecules that comprise the nachos are still nachos after you masticate and digest them.”
Question #2: “What is ‘you’?”
Hank asks: if you swallow a ping pong ball, is the ping pong ball then a part of you? “I would venture to say no, it’s not part of me,” says Hank.
“In fact, your digestive system is sort of not inside of you,” he explains. “Your GI tract is a long, complicated, tightly-controlled tube of outside that runs through your inside. If you take out stuff from your digestive system, there’s a lot of stuff that isn’t you, including the several kilograms that live inside your gut. By mass, the average human is about 3% gut bacteria.“
Hank goes onto explain that, in the end after digestion, about one-third of your nachos will have never left your digestive system and they will be in your feces in a day or two. The rest of the atoms and molecules will be breaking down more slowly to feed you, some of them expelled in your urine and feces and others expelled in the carbon dioxide that you exhale.
But it turns out a part of those nachos will end up as a part of you. Hank says,
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