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Artículo When we lose weight, where does all the fat go? Food


When we lose weight, where does all the fat go?



Antonio J. Rodríguez

09 Diciembre 2016 16:36

With a worldwide obesity crisis occurring, we should all know the answer to the simple question of where the fat goes.

Despite our culture of body worship and our obsession with dieting, many health professionals aren’t sure where fat goes when people lose weight. Many think they know, but when pressed their answers prove that confusion and misconception abound.

The excess fat from our stomach, legs, arms, jowls, and buttocks obviously turns into something else. But most of us don’t know what. Each of us stores fat in a different way, depending on our gender and hereditary aspects. It’s no secret that men accumulate fat around the belly, while women tend to store it on their hips.

The most common misconception among doctors, dieticians and personal trainers is that body mass is converted into energy, heat, or muscle. This is false. Any kilos you manage to lose after sweaty sessions at the gym don’t turn into extra energy or get absorbed into your biceps. That would be too good to be true.

If we want to know what happens each time a woman reduces her chest size, or a man finds he can slip into a t-shirt he hasn’t worn in years, we must turn to science for the answer.

Ruben Meerman, physician and Australian TV science presenter, grew interested in weight loss after a personal experience:

I lost 15 kilograms in 2013 and simply wanted to know where those kilograms were going. After a self-directed crash course in biochemistry, I stumbled onto this amazing result

Ruben Meerman

Together with Professor Andrew Brown of the University of New South Wales (UNSW), Meerman decided to clear up the matter once and for all. "There is surprising ignorance and confusion about the metabolic process of weight loss," says Professor Brown.

"The correct answer is that most of the mass is breathed out as carbon dioxide. It goes into thin air", says Meerman. And since the carbon dioxide we exhale is invisible, we can’t see it leaving out bodies.

So, that’s it? The fat just vanishes?


In their article, published in the British Medical Journal, the authors show that the loss of 10 kilograms of fat requires 29 kilograms of oxygen to be inhaled. If you follow the 10 kilograms of fat as they are "lost", 8.4 kilograms of those are exhaled as carbon dioxide via the lungs. The remaining 1.6 kilograms become water, which can be excreted in urine, faeces, sweat, breath, tears, and other bodily fluids.

Two frequently-asked questions have arisen from this surprising new study: Is it possible that weight loss may be contributing to global warming?

"This reveals troubling misconceptions about global warming which is caused by unlocking the ancient carbon atoms trapped underground in fossilised organisms. The carbon atoms human beings exhale are returning to the atmosphere after just a few months or years trapped in food that was made by a plant,” says Meerman.


Can breathing more cause weight loss?

Unfortunately, no. Breathing more than required by a person’s metabolic rate leads to hyperventilation, which can cause dizziness, palpitations, and loss of consciousness.

Meerman and Professor Brown recommend that these basic concepts be included in secondary school curricula and university biochemistry courses to correct widespread misconceptions about weight loss among health professionals.

With a worldwide obesity crisis occurring, we should all know the answer to the simple question of where the fat goes. The fact that almost nobody could answer it took us by surprise and we realised how poorly this topic is being taught