Home Did You Know True or False: Fat Is Converted to Energy When Burned

True or False: Fat Is Converted to Energy When Burned

by Erika Nicole Kendall

A quick look at what it takes to burn that body fat:

The most common misconception among doctors, dieticians and personal trainers is that the missing mass has been converted into energy or heat.

“There is surprising ignorance and confusion about the metabolic process of weight loss,” says Professor Andrew Brown, head of the UNSW School of Biotechnology and Biomolecular Sciences.

“The correct answer is that most of the mass is breathed out as carbon dioxide. It goes into thin air,” says the study’s lead author, Ruben Meerman, a physicist and Australian TV science presenter.

In their paper, published in the British Medical Journal today, the authors show that losing 10 kilograms [or ~22lbs] of fat requires 29 kilograms of oxygen to be inhaled and that this metabolic process produces 28 kilograms of carbon dioxide and 11 kilograms of water.


If you follow the atoms in 10 kilograms of fat as they are ‘lost’, 8.4 of those kilograms are exhaled as carbon dioxide through the lungs. The remaining 1.6 kilograms becomes water, which may be excreted in urine, faeces, sweat, breath, tears and other bodily fluids, the authors report.

“None of this is obvious to people because the carbon dioxide gas we exhale is invisible,” says Mr Meerman.

Did you think fat was converted to “energy” since fat is “stored energy?” You’re not alone.

More than 50 per cent of the 150 doctors, dieticians and personal trainers who were surveyed thought the fat was converted to energy or heat.

“This violates the Law of Conservation of Mass. We suspect this misconception is caused by the energy in/energy out mantra surrounding weight loss,” says Mr Meerman.

Did you think fat was “converted to muscle,” too? You’re not alone, either. In fact, in the very beginning, so did I:

Some respondents thought the metabolites of fat were excreted in faeces or converted to muscle.

“The misconceptions we have encountered reveal surprising unfamiliarity about basic aspects of how the human body works,” the authors say.

But… can you lose weight simply by breathing more?

The answer is no. Breathing more than required by a person’s metabolic rate leads to hyperventilation, which can result in dizziness, palpitations and loss of consciousness.

When you are active, your heart increases your blood pressure in a way that helps deliver oxygen to your muscles and keep blood flowing adequately. Trying to artificially increase your blood pressure without having the movement that actually needs the oxygen means it’d all go straight to your head. That’s where the dizziness comes from.

Remember – when you breathe in oxygen, you exhale carbon dioxide. Plants consume your carbon dioxide, as a part of photosynthesis, and release oxygen (because plants consider oxygen waste) back into the atmosphere. That’s why it’s so important for us to have plants in as many spaces as possible.

That being said, if you thought weight loss somehow could contribute to global warming by increasing humans’ carbon footprint…

“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 Mr Meerman, who also presents the science of climate change in high schools around Australia.

*What’s the takeaway, here? Your body is constantly burning energy, all day long. It’s burning the food you eat—remember, on a rudimentary level, food is fuel—and it’s also burning body fat. (In cases of starvation, it’s burning muscle, too.) If you want to speed up the fat burning process, you’ll want something that will naturally compel your body to breathe harder and, yes, work harder because, remember, trying to just breathe harder without doing the work that requires the exercise causes dizziness and, ultimately, fainting. That thing that will compel that is exercise.

If you truly want to see a loss of body fat, you’ll want to make sure the following are a part of your workout regimen: 1) a high-intensity workout plan; 2) a diet high in fresh produce that can keep you regular and energized; 3) a solid amount of fluids, preferably water; 4) sweating!

Source: Study: When you lose weight, where does the fat go?

*Some folks told me they were confused by this, so I stepped out of my nerd zone for a moment and tried to clarify what the takeaway should be, here. Basically, if you want the fat burn you’ve got to put in actual work and challenge yourself in a way that gets your heart going—and that will mean different things for different people—if you want to see those results!

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