Even most supposed experts get this wrong. In 2014, the authors of a study surveyed 150 family doctors, dieticians, and personal trainers with the question: When someone loses fat where does the fat go? The vast majority thought it was converted to energy or heat. Some believed it was eliminated from the colon as food waste or, best of all, converted to muscle (if only!). Only 3 of the 150 got it right. So, what’s the answer?
“[F]at is converted to carbon dioxide and water,” the scientists behind the study wrote. “You exhale the carbon dioxide and the water mixes into your circulation until it’s lost as urine or sweat.” They discovered that 84% of the bodyfat we lose comes out through the lungs. The remaining 16% turns to water, where it’s mostly lost when we pee or sweat, though it may also exit with other bodily fluids. “In other words, nearly all the weight we lose is exhaled,” the scientists wrote.
And it’s not just a bodyfat thing. They went on to state that “almost everything we eat comes back out via the lungs. Every carbohydrate you digest and nearly all the fats are converted to carbon dioxide and water.” This is how it moves about the body, whether it stays or leaves. The same is true for alcohol and protein, apart from a small amount of protein that’s turned into urea and other solids and excreted as urine. The only food that arrives at your colon undigested is dietary fiber.
But back to the bodyfat. Putting a finer point on it, the scientists wrote: “Our calculations show that the lungs are the primary excretory organ for fat. Losing weight requires unlocking the carbon stored in fat cells, thus reinforcing that often-heard refrain of ‘eat less, move more.’”
So, will breathing deeper or faster help you lose weight? And could a face mask hinder fat loss?
No and no. Breathing is merely the way that fat (and carbs and protein), converted to carbon dioxide, finally exits your body. It’s like the door on a jail. When fat is free it leaves. The hard part is getting the fat out of jail—or, to carry on this metaphor, never getting the original calories locked up. Fat loss via breathing is an interesting scientific fact. But losing fat is accomplished via diet and, to a lesser degree, exercise.
See also: 5 Sneaky Ways to Burn Fat