What Actually Happens to Your Fat When You Lose Weight? Where Does It All Go?

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Weight loss is something that crosses pretty much every person’s mind at one time or another.

Maybe the holidays come round, and we overindulge. Or maybe we start to stress-eat because of a major new project at work. Or maybe we get pregnant, and after giving birth we want to get back to the pre-baby body. No matter how it happens, it happens to everyone – you gain a few extra pounds, and then have to work it off somehow.

But when you lose weight, what actually happens to the fat in your body?

According to New South Wales professor Andrew Brown and former physicist Ruben Meerman, when you lose weight, you actually exhale the excess fat as carbon dioxide. Together, they’ve come up with new calculations based on biochemistry, which have been published in the British Medical Journal.


The two spoke out their findings in a press release:

“There is surprising ignorance and confusion about the metabolic process of weight loss. The correct answer is that most of the mass is breathed out as carbon dioxide. It goes into thin air.”


Triglycerides (a type of fat) are made of carbon, hydrogen, and oxygen, and they are metabolized when you lose weight. To expel them, our bodies turn them into carbon dioxide – which gets exhaled – and water, which is expelled through sweat, urine, and other bodily fluids.

The vast majority of what used to be fat exits through our lungs, though, making them the primary organ for weight loss.


Don’t try just breathing faster or more often to shed pounds, though – you’ll just get dizzy and find yourself with a racing heart before (maybe) passing out.

Even though the new information explains how the fat disappears from our body, there’s nothing novel in how we convert those fat cells to the carbon, oxygen, and hydrogen particles that can be expelled – you’ll have to go the tried and true route of diet and exercise.

No fun, perhaps, but the results will come!