Despite society’s obsession with weight loss, a new study reveals that, surprisingly, most health professionals don’t actually know what happens to fat when we “lose it”.
The research conducted by a team at UNSW Science in Sydney calculated exactly what happens to our fat when we shed kilos, and revealed that doctor's leading theories are wrong - we don’t convert our missing mass into heat or energy, we breathe it out.
Their results, published in the British Medical Journal, reveal that 10 kg of fat turns into 8.4 kg of carbon dioxide, which is exhaled when we breathe, and 1.6 kg of water, which we then excrete through our urine, tears, sweat and other bodily fluids.
“The correct answer is that most of the mass is breathed out as carbon dioxide. It goes into thin air,” said lead author of the paper Ruben Meerman, a physicist and TV presenter, in a press release.
Meerman first became interested in the biochemistry of weight loss when he dropped 15 kg - but when he asked doctors where this weight went, he was surprised by the fact no one could tell him.
After surveying 150 doctors, dieticians and personal trainers, he discovered that more than half thought that fat was converted into heat or energy as we break it down.
But, as a physicist, Meerman knew that this would violate the Law of Conservation of Mass.
To figure out the answer once and for all, Meerman partnered with Andrew Brown, head of the UNSW School of Biotechnology and Biomolecular Sciences, and the team started calculating the biomolecular reactions that result in weight loss.
We put on weight when excess carbohydrates and proteins that we've eaten are converted into triglycerides (compounds made up of carbon, hydrogen and oxygen) and are then stored in lipid droplets inside fat cells. To lose weight, you need to break down those triglycerides to access their carbon.
The results showed that in order to completely breakdown 10kg of human fat, we need to inhale 29 kg of oxygen (and somewhere along the way, burn 94,000 calories). This reaction produces 28 kg of CO2 and 11 kg of water.
“Our calculations show that the lungs are the primary excretory organ for fat,” the team writes in the paper.
However, they couldn’t work out exactly what was happening to the fat cells in this reaction. After months of research, Brown discovered a formula from a paper published in 1949 that solved the problem - it showed that oxygen atoms are shared between the carbon and hydrogen in fat at a ratio of 2:1 (forming carbon dioxide and water)
This allowed them to come up with the final figure of 84 percent of a fat molecule’s atoms being exhaled as carbon dioxide, and the remaining 16 percent ending up as water.
Meerman and Brown, BMJ (2014)
But unfortunately this doesn’t mean that simply breathing deeply will help us lose weight - we still need to do the exercise to unlock the carbon and break down the fat in the first place.
"You can only breathe so many times a day; on a day of rest, you breathe around 12 times a minute so 17,280 times you'll breathe in a day and each one takes 10 milligrams of carbon with it, roughly," Meerman told ABC Science. "So there's your limit on how much you're going to lose in a day with no exercise."
But will all this fat we’re breathing out will contribute to climate change? The short answer is no.
“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,” said Meerman in the release.
The funny thing about all of this is that, although most health professionals don’t know what happens to fat when we lose weight, most Veritasium viewers probably do. In fact, as this mind-blowing video below explains, not only do we lose our "lost" fat through breathing, if we were in a closed system, we would actually become trees.
짧게 줄이자면,
윗 글은 우리 체중이 감소될 때, 지방이 어디로 가느냐 하는 의문에 대한 답입니다.
호주의 연구진은, 체중감량 시 줄어든 지방이 어디로 사라지는가를 추적해 보았다고 합니다.
많은 의사들이 체중감량의 중요성은 역설하면서도, 막상 그 지방이 어디로 가느냐고 물으면 쉽게 대답하지 못한다는 점에서 연구주제를 찾았다고 하는군요.
놀랍게도, 지방의 대부분은 이산화탄소 상태로 날숨으로 내보내집니다.
즉, 10KG의 지방에다 29KG의 산소를 더하면, 28KG의 이산화탄소와 11KG의 물이 만들어지는거죠.
즉, 10KG의 지방 감량을 하신 분은, 28KG의 이산화탄소를 배출하신겁니다. 기체상태니까 28kg이라면 무지막지한 양이죠.
헉! 그렇다면 심호흡을 하는것만으로도 살을 뺄 수 있다는건가요? 저를 비롯한 과체중 보더들에게는 솔깃한 이야기가 아닐수 없습니다만..
안타깝게도 그건 불가능하겠죠.
윗 글에 따르면, 편안한 상태에서 성인은 1일에 약 17280번의 호흡을 하고, 한 호흡당 약 10밀리그램의 탄소를 배출한다고 합니다. 즉 하루종일 숨쉬기만 해서는 172800 밀리그람, 즉 0.172 KG의 탄소가 배출되네요 ㅋㅋㅋㅋㅋㅋㅋㅋㅋㅋㅋㅋ. 절망.
유산소운동이 살 빼는데 도움이 되는 이유가 바로 이것이네요. 지방이 가수분해되어 배출되어 대기타고 있는 탄소에, 산소를 최대한 많이 밀어넣음으로써 이산화탄소를 최대한 많이 만드는거죠.
즉, 윗 글은 다이어트 비법을 소개하고 있는 것이 아니라, 질량보존의 법칙이 우리 몸 안에서 어떻게 지켜지고 있느냐를 보여주는 과학 토막상식이랄까요?
마나님은 실망이 크시겠지만, 역시 살 빼는건 그저 숨쉬는 것 이상으로는 움직여줘야 하나 봅니다.
