Most (85-90%) of the carbon in the food we eat is breathed out, not excreted

Side note - it always amazes me (and people when I tell them) that when you lose fat from your body, they main way for that fat to leave your system, is to burn it then breathe the co2 out - that is one of the limits on how much fat you can burn a day. You do lose some of the results of the burning, and a little through sweat, but the vast majority is down to co2 leaving your system.

(Note you can temporarily also lose weight through water loss - but that isn't the loss of actual fat from your system.)

Yes it's the inverse of Feyman's comments how a tree's mass comes from what is pulled out of the air, not the ground

Turns out, we were the carbon captor all along

We need to figure out how to make 8 billion humans act as carbon sinks!

Splice tree dna, make groot a thing irl