(Click image for source)
I'll be honest, I was a bit taken back by this fact when I first learned about it.
Did you know that when you burn fat via exercise, diet, what have you - 80% of that lost fat gets breathed out through your lungs? I always thought you just pooped it out or something, but that's not the case.
The molecular makeup of human adipose tissue (fat) is C55H104O6. That means there are 55 Carbon atoms, 104 Hydrogen atoms, and 6 Oxygen atoms in a fat molecule. When your body burns fat it is caused by a chemical reaction that breaks down these molecules into smaller molecules. All the Carbons, Hydrogens, and Oxygens all break apart and form new molecules like H2O (water), and CO2 (carbon dioxide).
In fact 20% of a fat molecule breaks down to water and 80% breaks down to Carbon Dioxide...and how does your body get rid of Carbon Dioxide? Through the lungs!
(Click image for source)
Now I know what you're thinking...if there's only 6 Oxygen atoms in a fat molecule compared to 55 Carbon and 104 Hydrogen, then how is it able to break down into so many H2O and CO2 molecules with such a shortage of Oxygen atoms? Well....that's where breathing comes in! When you inhale fresh air it contains a combination of Nitrogen, Hydrogen, and Oxygen. The Oxygen atoms you breathe in are absorbed into your blood stream and used as a catalyst for fat oxidation (burning). The Oxygen atoms fuel the chemical reactions that burn fat and these Oxygen atoms are bonded with the molecules to form CO2 and H2O! The H2O eventually makes its way through the kidneys via the blood stream, and into your bladder, or ejected via sweat - whereas the CO2 gets transported to your lungs (via blood stream) to be ejected from the body via exhaling.
Pretty neat ey?
Here's a very weird video I found on YouTube on this process...
Sources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6755313/
https://www.bmj.com/content/349/bmj.g7257
https://www.bbc.com/news/health-30494009
