Fat Goes into ‘Thin Air’ When You Lose Weight

No matter which latest diet fad you see in the news, there’s always a constant line you’ll have thrown your way: "Burn fat with the <insert diet name here>."

Now, I’m not here to tell you whether your diet works or not. You’ll be able to tell that for yourself.

But I am here to let you know what really happens to all that fat when it disappears from your body.

Your personal trainer, your dietitian and even your doctor will tell you how you "burn" the fat away into energy or heat. And how you can literally feel this sensation, in the form of warmth and sweat, when you’re exercising.

Yet, a recent study by Australia’s University of New South Wales proves this simply isn’t true.

"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 of fat (about 22 pounds) requires 29 kilograms of oxygen to be inhaled (a little over 63 pounds). This metabolic process produces 28 kilograms of carbon dioxide and 11 kilograms of water.

The study was actually created out of interest from Mr. Meerman’s personal experience with weight loss.

"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," he says.

"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 me by surprise, but it was only when I showed Andrew my calculations that we both realized how poorly this topic is being taught."

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, feces, 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.

More than 50% 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.

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

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

Mr. 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.

So, how can you "burn" more fat? One way we’ve discussed in this space is to consume all your daily calories between noon and 8 p.m. Another is to work out in shorter, more-intense bursts.

Now that we know fat goes into "thin air," so to speak, I’d love to know what strategies for "losing" (instead of burning) fat work best for you. Give us your best ideas in the comments section!

Happy and healthy investing,

Brad Hoppmann


Uncommon Wisdom Daily

Your thoughts on “Fat Goes into ‘Thin Air’ When You Lose Weight”

  1. I think that we should eat a lot less sugar and do more physical exercise. If we exercise more
    then we breath more air and so loose more weight.

  2. The low carbohydrate diet is more efficient for metabolizing fat since one can maintain some level of ketosis. In ketosis fat is metabolized into acetylacetic acid (a four-carbon molecule) which is excreted into the urine. Loosing fat in four carbon pieces is faster than it just single carbon molecules (carbon dioxide).

  3. It’s the same process as in your car’s engine. It occurs as a big surprise to us that our very own aspect is a lot more primitive than what we imagine.

    What is interesting however, that there are countless observations about human ability to derive energy from nowhere under certain conditions. Or, maybe just not use any energy in such cases.

  4. Hi, Brad.

    Your conclusion here is spot on. However, Mr. Meer’s criticism is off the mark. The process of oxygenating carbon-hydrogen compounds is the same whether they are hydro-carbons in your car or campfire, or carbo-hydrates (or fats or proteins) in your diet. The body uses enzymes to allow the process to take place at body temperature, but it is the same process: O2 breaks carbon-hydrogen molecule apart and combines with the C to make CO2 (or CO, carbon monoxide, if the burning is incomplete), and H2O. That’s why you have water dripping out of the tailpipe of your car, and why you fog a mirror when you breathe on it.

    The exhaust goes into thin air – correct. In fact, potato chips produce water in the body. But in all these cases, the purpose is to release calories, which indeed are units of heat, i.e. energy. It is absolutely a “burning” process, no more a violation of the Law of Conservation of Mass than roasting marshmallows with the cub scouts. This is simple physics. The mass is unchanged; only the molecular bonds have been broken, releasing energy. Why Mr. Meer sees a need to complicate it is a mystery to me. Still, your conclusions are correct.

    Thanks for all you do, and for sharing your research with us.

  5. This is nothing new. I learned it in high school in the 1960s. Maybe our secondary education curricula has been degraded since then. “Burning” is simply a process of oxidation. When you “burn” wood, you turn it into CO2 and H2O, The same thing happens with sugars and fats in the human body (although the process of converting fat to glucose is more complex). You oxidize carbon and hydrogen (carbohydrates) by adding oxygen to carbon to form CO2 and oxygen to hydrogen to form H2O. Both oxidative processes produce energy, mostly in the form of heat.

  6. Greer Childers Body Flex is a system of weight loss that I now believe works based on this article. Her breathing exercise for burning fat is not something you would want to subject anyone to watching. Do it in the privacy of your own room, out of sight. Her idea is that it is oxygen that burns fat not the exercise.

  7. The article is talking about burning fat, but the diagram shows glucose being converted to carbon dioxide and water. How does the fat get converted to glucose ? The discussion needs to also talk about auto-immune problems with fat metabolism – ie what if the fat tissue does not receive the signals to release fat ?

  8. So how exactly did it end up turning into Carbon Dioxide? I think I’ll look up his work and read up on it. Thanks for getting me interested in the topic.

  9. I’ve noticed that when walking 1.25 miles on a treadmill at 2.9 mph, three mornings a week, I breathe a lot faster and sweat a little. I take in a lot of extra oxygen and breathe out a lot of extra carbon dioxide. In fact, I set the grade and speed of the treadmill to insure that I do not run out of oxygen during the 26 minutes I walk (I’m 81 years of age). So, now, because of your article, I know where all that extra oxygen is going. Thanx a bunch.

  10. Could it be that doing aerobic activities which make one breathe harder and faster would help?

  11. I keep my weight in check by hiking and love making. Seriously , it is said that making love uses more calories than almost any other activity.

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