It's a mystery most of us never think about — when you lose weight, where does the weight go? Well, it turns out the answer is just as strange and unexpected as the question: you exhale it. As in, when you are burning off fat, you are literally breathing it out. Weird.
This new info comes via a study published in the British Medical Journal by researchers at the University of New South Wales and Rueben Meerman, an Australian physicist turned TV personality and science educator (which sounds kind of like an Australian Bill Nye). According to their research, when the body breaks down triglycerides (the primary molecule that makes up human fat), it converts the molecules into carbon dioxide, water, and energy. The energy is used by the body, the water is presumably lost through sweat or other bodily fluids, and the carbon dioxide — which is the largest bi-product of this chemical reaction — is exhaled.
These new findings obviously fly in the face of most conventional wisdom about weight loss. "Most people believed that fat is converted to energy or heat, which violates the law of conservation of mass," the study states in its discussion of misperceptions surrounding what happens to fat that's burned off. "Other misconceptions were that the metabolites of fat are excreted in the faeces or converted to muscle." But in reality, most of the fat molecules are converted to carbon dioxide and simply breathed out.
Isn't the human body wild?
Of course, it's worth noting that simply breathing isn't going to cause you to burn fat, not unless your breathing is effortful enough to actually require you to use up some of the energy your body has stored in your fat cells. So sitting around hyperventilating isn't going to do much for you. On the other hand, the fact that our bodies have come up with such a simple and efficient way of disposing of the bi-product of metabolizing fat molecules is pretty cool. Rather than some super complicated disposal process, all you have to do is breathe.
So the next time you're panting after a run, enjoy it. You're actually breathing out your excess pounds.