Wait, what? Scientists say fat is exhaled as carbon dioxide during weight loss

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Ever thought that fat loss through exercise is converted into energy or heat?

Think again. 

The right answer is that 84 per cent of fat is exhaled as carbon dioxide and the remainder as water. 

“It goes into thin air,” says Ruben Meerman, a physicist and lead author of a fascinating study published in the British Medical Journal.

The study states that for every 10kg lost, 8.4kg will be breathed out as air and the rest will turn into water in the form of urine, perspiration, tears and so on.  

It also reveals that losing 10kg requires 29kg of oxygen to be inhaled and that this metabolic process produces 28kg of carbon dioxide and 11kg of water.

Meerman and fellow author Andrew Brown from The University of New South Wales (UNSW), said: "None of this biochemistry is new, but for unknown reasons it seems nobody has thought of performing these calculations before." 


Surprisingly,  most of 150 doctors surveyed by Meerman could not get the answer correct.

Only three of the health professionals knew the right answer.

"Basically in fat there are three types of atoms - carbons, hydrogens and oxygens," said Professor Brown, head of UNSW’s School of Biotechnology and Biomolecular Sciences.

“You know that the carbons have to come out as carbon dioxide and the hydrogens have to come out as water.

"And then Ruben went back to a paper from 1949 which did some clever biochemistry to show you how the oxygen is partitioned between the carbon dioxide and the water."

But can you can breathe away all your fat?

Meerman said: "The answer is no, unless you’re moving more, that’s called hyperventilation."

Source: Herald Sun, BBC, ScienceDaily

Body fatWeight LossUncategorisedAndrew Brown