11 thoughts on “My new TEDxBundaberg talk about breathing and weight loss

  1. Hi Ruben,
    Thanks for all the great information you provide online. I have a question about a surprising result from my Garmin fitness tracker following my breathwork sessions. The Garmin is a wristwatch device that measures heart rate and provides, among other things, estimates of caloric burn for various activities, apparently based on time between heartbeats and my height/weight data. According to the watch, my Wim Hof-style deep breathing sessions (which last about 25 minutes) burn nearly 700 calories! The calorie burn estimates for my other activities are within the expected range so I don’t think the device is defective. Is it possible that the breathwork estimate is correct? If so, would that be due to the expiration of carbon dioxide itself or to the physical work required for deep breaths? Thanks for any clarification!

    1. Hi Rebecca,
      Good question. I’m not familiar with the algorithm the Wim Hof Method app uses to calculate energy expenditure or how it was validated (it’s also available for the Apple Watch) but exposure to cold can cause up to a five-fold (5x) increase in the resting metabolic rate. That means you’d be consuming 5x more O₂ and producing 5x more CO₂ than when you’re in the “thermoneutral zone”. The average resting metabolic rate for women is ~1400 kcal/day, which is roughly 1 kcal/minute. A five-fold increase therefore raises the metabolic rate of an average woman to ~5 kcal per minute so, at that rate, you would expend 125 kcal in 25 minutes. Your 700 kcal figure does sound a bit high but I am not sure what else you’re doing during Wim Hof breathing session? The “work of breathing” is about 0.3 to 0.6 joules per litre of air. Adults breathe about 360 litres of air per hour so that’s 108 to 216 joules, or 25 to 50 kcal, which does not account for the addition 575 kcal… but perhaps there is additional physical activity in the Wim Hof method that does for that. I’m not sure but hope that helps to get you started.

  2. I appreciate this reply and the explanation of the “work of breathing.” My breathing sessions don’t involve much movement apart from breathing – exceptions might be some exaggeration in the chest to accommodate very deep breathing and also periodic “breath retentions” for one to two minutes after exhaling. So I suspect the 700 kcals overstates my exertion. Cold exposure is also key to the program (not during deep breathing sessions) so I’m very encouraged by the significant increase in resting metabolic rate!

  3. Dear Ruben,
    I am very interested in science since I was a little child. So I always thought about the exact same thing as you. The more you respire, the more you can eat. But then I was thinking about anaerobic fermentation. That would happen whenever you don’t breathe properly. When that happens, you don’t have enough oxygen to respire normally and therefore also don’t loose weight, even though you are exercising, because the carbon doesn’t leave the body due to missing oxygen to pair with.
    This would lead to the conclusion that it is very important to learn how to breathe properly. Also, you should train your lungs and heart so that they can provide enough oxygen.
    Today I saw your Ted talk and I found that all my thoughts were there except for this last one. How do you think about it?


    1. Dear Rashid,

      Good to hear from a fellow lover of science. This is actually a very frequently asked question with a very surprising answer.

      The first surprise is that the oxygen molecules we inhale do not become the “O₂” in the CO₂ we exhale. Inhaled oxygen is converted to water.

      This happens in a series of chemical reactions catalysed by enzymes collectively referred to as the “electron transport chain”. The enzyme that splits molecular oxygen (O₂) into two separate oxygen atoms (2 × O) is called “cytochrome C oxidase”. The hydrogen atoms added to the oxygen atoms to form the final product (H₂O) of these reactions all come from food.

      But that leaves another question: where do the oxygen atoms in exhaled carbon dioxide come from?

      The answer is water molecules and it happens in the Krebs cycle, also known as the citric acid cycle, or the tricarboxylic acid cycle (TCA) cycle.

      The hydrogen atoms that are removed from the H₂O in the Krebs cycle are used in the electron transport chain, where they are married to the oxygen atoms we inhale. This all seems very redundant and unnecessarily complicated but that’s aerobic respiration works.

      In the absence, or during a shortage, of oxygen molecules, the hydrogen atoms removed from H₂O in the Krebs cycle get “stuck” with nowhere to go, and the process grinds to a halt. When this happens in a muscle, glucose is “fermented” to lactate. That, in itself, is a two-step process. Glucose is first split in half to form two pyruvate molecules, and these are both converted to lactate. The lactate molecules produced are then transported to the liver, where they are converted back to pyruvate, and then back to glucose in a process called the Cori cycle.

      All of this happens in all of your cells, not just in your lungs. Therefore – and to finally answer your question – it does not really matter “how” you breathe. As long as there are enough oxygen molecules and water and food molecules floating around in your cells, they can carry on doing what they do.

      However, “how” you breathe can affect the amount of carbon dioxide in your blood. Hyperventilating will remove more CO₂ than you produce, and will lead to a condition called “hypocapnea” which means “not enough CO₂ in the blood. This can manifest in a constellation of symptoms including dizziness and potentially a loss of consciousness. Hypoventilation (i.e. not breathing enough) can lead to hypercapnia, too much CO₂ in the blood, and a different set of symptoms.

      Regards, and I hope that helps,


  4. Nice, but as a scientist (I’m a math professor) I have to disagree with your math. You claim that 10 kg of fat gets turned into 8.4 kg of CO2 and 1.6 kg of H20, but that doesn’t make any sense to me. If you use the chemical formula at 1:58 you get that in order to burn 10kg of pure fat you have to inhale 25.9 kg of oxygen, which then gets turned into 25.1 kg of CO2 and 10.8 kg of H2O. So basically, you exhale as much as you inhale and you end up with approximately the same weight of water as you had fat!

    1. Dear Sander,

      Thank you for checking in. It’s great to hear from people who enjoy these numbers.

      That slide did not translate into the video very clearly, unfortunately, but there is a brief moment when all the numbers are correctly displayed. You can get a longer look at them in the published paper on the British Medical Journal’s website (Figure 2, Page 3):

      It actually takes 29.0kg of oxygen to fully oxidise 10kg of fat (not 25.9kg), so we start with a total of 39kg of reactants. The complete oxidation produces a total of 28kg of CO2 and 11kg of H2O.

      Of the 28kg of carbon dioxide, 8.4kg comes from the atoms in the fat, and the remaining 19.6kg comes from the atoms in the oxygen.

      Of the 11kg of water, 1.6kg comes from the oxygen atoms in the fat, and the remainder comes from the oxygen.

      I hope that clears up the confusion.

      Kind regards,


  5. Ruben, your TEDx Talk was fantastic. I can only learn and remember by illustrations, is there somewhere I can get a copy of all the slides from your TEDx talk. I didn’t do science at school years ago, now I wish I had, ironically I took Home Economics now I am trying to get rid of 20kg, your talk was so clear to me, I need to learn about atoms.

    1. Dear Jenny, apologies for the delayed reply and many thanks for your kind words. I don’t have my slides in a format that works very well on a static page… each one has multiple animations so they’re a mess when printed as PDF’s. There’s no need to have any regrets about not doing science at school because the science curriculum did not and still does include any of these concepts in a sequence or format that allows students to connect all the dots between their stomachs and their lungs. As I said in the TEDx talk, the trick to losing weight is to exhale more carbon atoms than you eat. There is already a tried-and-tested, scientifically validated way to do that, which is to count kilojoules (or calories if that’s your preferred units). In fact, dietitians measure metabolic a person’s metabolic rate by measuring how much oxygen they consume and carbon dioxide they exhale per minute. Calorie counting has become so unpopular that some people claim it doesn’t work, but it most definitely does. Good luck with your weight loss. I found cutting out the 3-4 large cappuccinos I was smashing everyday to be a very effective way to reduce my intake because that’s one litre of milk, which is a whole meal worth of extra calories on top of what I was eating… and walking for an hour or more a day.

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