체중 감량과 운동에 관한 속설의 과학적 근거

### 체중 감량의 복잡한 과학: 운동만으로는 충분하지 않은 이유
* 🏋 체중 감량은 어려운 일이며, 칼로리로 측정된 음식에서 얻는 에너지와 원료를 필요로 하는 생물학적 메커니즘으로 인해 신체는 종종 **자신에게 불리하게 작용**합니다.
* 🔥 체중을 줄이려면 섭취하는 칼로리보다 더 많은 칼로리를 소모해야 하는데, **걷기와 같은 활동은 시간당 약 260칼로리를 소모**하고 **달리기는 최대 700칼로리를 소모**할 수 있습니다.
* 📉 그러나 체중 감량을 위해 운동에만 집중하면 **운동으로 인한 칼로리 소모가 미미**할 수 있고 다른 생활 영역의 활동 감소로 인해 균형을 맞출 수 있다는 연구 결과가 있기 때문에 기대하는 결과를 얻지 못할 수 있습니다.
* 🔍 산업화된 사회와 하자족과 같은 수렵 채집 사회를 비교한 연구에 따르면 두 그룹 모두 **매일 비슷한 칼로리를 소모**하는 것으로 나타나 활동량이 증가하면 칼로리 소비량이 훨씬 더 높아진다는 가정에 도전하고 있습니다.
* 💪 근육은 휴식 시 지방보다 더 많은 칼로리를 소모하지만, 에너지를 소비하는 다른 신체 과정에 비해 **체중 감량에 미치는 전반적인 영향은 상대적으로 작습니다.**
* ⚖ 우리 몸은 고정된 칼로리 예산을 유지하며, 운동을 시작하면 무의식적으로 다른 움직임을 줄여 **지속적인 지방 감소를 달성하기 어렵게 만들 수 있습니다.**
* 🧠 인간의 진화적 배경은 우리를 효율적인 칼로리 수확자로 만들었고, 이는 게으름보다는 **과식하려는 타고난 욕구**로 이어져 현대 비만의 중요한 요인으로 작용하고 있습니다.
* 📚 건강과 삶의 질을 향상하려면 평생 학습과 문제 해결 능력을 위한 도구를 제공하는 **Brilliant와 같은 리소스**를 통해 체력과 정신적 민첩성 사이의 균형을 찾는 것이 필수적입니다.

운동은 신체가 적응하고 안정적인 칼로리 예산을 유지하기 때문에 체중 감량을 위한 신뢰할 수 있는 방법이 아닙니다.

Losing weight is hard, and unfortunately, your body is sabotaging you every step of the way. Your body is a biological machine that follows the laws of thermodynamics and needs energy and raw materials to stay alive, which is why you eat. The energy from food is measured in calories, and you need a certain amount to power your internal machines. Your brain thinks, your heart pumps, your gut digests, your immune system immunes. And you contract your muscles to move around. The harder a movement is, the more calories you burn. An hour of walking burns about 260 calories, moderate swimming 430, biking 600, running 700. If you eat more calories than you burn, your body stores them mostly in the form of fat. One kilogram, or two pounds, of fat is about 7000 calories. Seems simple. To lose weight, you have to burn more than you eat, so fat is turned back into energy.

There are two ways to do this: Eating less – which we will cover in another video – and burning more, say by moving around aimlessly, also called working out. We also get told early on that exercising is healthy somehow, so working out should kill two birds with one stone. Unfortunately, this doesn’t exactly work out. It is one of these frustrating experiences where you do what you think is right only to not see the results you deserve. In reality, focusing on exercising is not a reliable way to lose weight. Some studies show that exercise can lead to some fat loss, others that it is minimal. How can this be? It turns out that until recently we fundamentally misunderstood what moving around a lot does to our bodies. Disclaimer: The science on fat loss is complicated and many studies compare vastly different populations, different measurements and are complicated to understand. And the online discussion is full of personal anecdotes. This video covers general principles,

based on the current state of research. But when you look at the individual, there are variations – it matters if you are an athlete or casually try to lose weight. The Myth of the Workout A few years ago scientists began to compare populations in industrialized societies, which sit a lot, to hunter-gatherer communities, who move around a lot. The Hadza people in Tanzania walk an average of 9 km a day to find wild plants and hunt animals, dig for tubers, climb trees for honey, or collect water. They can move more in a single day than an office worker in a week. So of course, they burn more calories, right? But it turns out that the Hadza burn the same amount of calories per day as a typical person in an industrialized country: around 1900 for women and around 2600 for men – which doesn’t make sense at all. It’s also not their genes, since it’s the same for other hunter-gatherer tribes.

So the confused scientists looked at similar measurements in individual countries. It got even stranger: Active people who work out regularly do burn more than inactive people. But only very little, often as low as 100 calories, the equivalent of a single apple. For some strange reason in the long term, the amount of calories you burn is often relatively unrelated to your lifestyle. Per kilo of muscle weight, your body has a relatively fixed calorie budget it wants to burn per day. Sure, if you want to gain muscles by pumping iron, you also need to eat more to build and sustain them or your new muscles wither away. But in total, your body keeps your calorie budget per unit of you, pretty stable. And to make matters worse, if you want to lose fat your body sabotages you in small and big ways: First of all, when you begin to work out regularly, maybe going for a run in the morning,

your body may subconsciously make you move less when you don’t pay attention. Maybe you take the elevator instead of the stairs, you sit more when you meet your friends or you sleep longer – largely balancing out your burn again, preventing you from burning much fat. You can overcome this temporarily: If you do actually change your life after sitting around for years and suddenly start working out without eating more, this is a shock to your system. You actually do burn more calories and lose fat – so you can lose weight through exercise! But this is often very short-lived. Your body adapts and burns fewer and fewer extra calories each week until it restores its original calorie budget. After a few months, you burn a very similar amount to what you did when you didn’t work out. If you stay really consistent, your burn might increase slightly and your body composition might change, but most people struggle with keeping up the habit.

if they don’t love the extra movement. Which is why so many people hit a weight loss plateau. Objection! What about muscles? Muscles burn 3 times more calories at rest than fat. This sounds impressive, but tissues like your brain, skin, or intestines burn way more. In absolute terms, a more muscular body composition makes a difference for how many calories your body burns, but it’s relatively small. Muscles matter a lot for health, longevity, and performance, but not that much for weight loss. Bizarre. And now we are getting to the actual reason why exercise is healthy. Why Your Body Is Sabotaging You. So your body has an activity budget per day that it wants to stick to. This setting evolved when humans had to move a lot. Not because they wanted to, but because they had to find food for survival. But when food is abundant and exercise is voluntary,

what does your body do with the energy that you are not using to move around? We are simplifying a lot here, and this is relatively new science, but in a nutshell: There are many different systems in your body trying to do their job as well as possible. And if there’s extra energy, they seem to use it. Unfortunately, this is bad. When your immune cells detect injuries or infections, they trigger inflammation. Fighter cells, alarm chemicals, and fluids flood into your tissue. This is crucial, but it also causes damage, so it needs to be cleaned up quickly or it can become chronic. And chronic inflammation is one of the major contributors to many serious diseases, from cancer to heart failure. If your immune system is on a tight budget, it has to be efficient with inflammation – with lots of free calories though, it overcommits. Another thing is that your glands produce hormones you don’t need. Like cortisol,

the stress hormone, which triggers your fight or flight response. Crucial for survival, but if you have too much of it you get, well, very stressed, all the time. Chronic stress is a major cause for a bouquet of health issues including your mental state. For our ancestors who moved a lot and had to deal with sudden bursts of activity, fleeing from a lion, attacking that bison, this cortisol was crucial – but if you live a modern, sedentary lifestyle your body is ready for action that doesn’t happen, hurting itself in the process. Your body evolved to move regularly and is fine-tuned to a certain base level of activity. If this activity is missing it still uses almost the identical amount of energy, just on stupid stuff. This is why you burn a similar amount of calories whether you work out or not. A lot of the energy you spend working out is energy you don’t spend on other physical activities and body processes.

Working out is not a magic bullet, but it seems to restore an internal physical balance that seriously affects your body. And this is also why regular exercise is so incredibly healthy; the evidence is incredibly clear here. It reduces chronic inflammation and stress, it is good for your heart, may ease depression, and makes you live longer and better. 

Why Humans Are So Hungry 

When your ancestors evolved, they had to work hard for calories. Sometimes it would be easy, and they could afford to chill out quite a bit. But in hard times, they had to move quite a bit to feed themselves, walk longer to find prey, or dig longer to find tubers. If extra movement burned more calories, this would lead to a spiral of starvation. The less food you find, the more energy you need to find food – which doesn’t even fill you up, because you moved more. It’s like taking on more debt when you are in

the red. It works for a while, but then you go bankrupt and die. So for your ancestors, being able to move a lot without burning extra calories was a matter of life and death. Ok. But this means the obesity epidemic of the modern world is not primarily caused by laziness, but by overeating. Humans evolved to be mad for calories. Because of our extremely hungry brains, and our extremely useless kids. Kids are cute but unlike other species, human kids have to be fed and cared for by adults for years before they become even remotely useful. Because the human brain not only eats up about 20% of all our calories at rest – twice as much as our closest ape relatives’ – it also takes a lot of time to develop through playing, learning and honing social skills – all the things that make us human. Our species is so extremely calorie-expensive to maintain that we became super-efficient

calorie harvesters. 5 hours of human hunter-gatherer foraging yields between 3,000 and 5,000 calories, while our ape relatives get no more than 1,500 in the same time. And we became so good at calorie harvesting precisely because of our big brains and years of social skill training. In a typical ancestral tribe, some members would spend the day searching for plants, others hunting or gathering honey, others nurturing kids. And at the end of the day, we’d share the calories so that no one would end up hungry. Being frenetic calorie harvesters seems to be deeply part of what makes us human. It's not a bug, but a feature. But today, it seems as if that feature has turned on us – we can’t stop overproducing food and overeating. If you want to lose fat, reducing calories is the biggest part of the answer. We’ll cover diet in the next part.

So to conclude: You will probably not lose nearly as much fat by working out as you hoped, but you will do something more important: give your body balance and make you more resilient and prevent or delay many of the diseases that will make your life miserable so you can enjoy a higher quality of life, for much longer. But physical fitness is only half the equation. To make the most of your long, healthy life, you also need a fit, active mind—one trained to navigate our fascinating world and agile enough to solve any problem. Which is where our friends at Brilliant come in. Brilliant will make you a better thinker and problem solver, with thousands of hands-on, bite-size lessons on just about anything you may be curious about—from AI and physics to math, data analysis, and beyond. On Brilliant, you’ll learn through discovery, by trying things yourself. And you’ll not only gain knowledge of key concepts, but learn to apply them to

real-world situations. All while transforming your mind into a lean, mean, thinking machine. We’ve also partnered with Brilliant to create a series of lessons to take your scientific knowledge to the next level. These lessons let you further explore the topics in our most popular videos, from rabies and mammalian metabolism to climate science and supernovae. I’ve told you my fair share of science stories over the years—and I still learned something new there. It’s like a one-on-one version of a kurzgesagt video. And you can get started whenever, wherever: right from whatever device you’d like. Brilliant is the perfect tool for building a life-long learning habit – one of the best ways to spend your lifetime if you ask us. To get hands-on with kurzgesagt lessons and explore everything Brilliant has to offer for free for a full 30 days, visit Brilliant.org/nutshell

or click on the link in the description. You’ll also get 20% off an annual premium subscription. Our latest journal just dropped on the shop. Get ready to be inspired: It’s our mission here at kurzgesagt to constantly discover new, exciting science and to present it to you in our videos. That's actually hard work. But we’re not alone. We are guided by our curiosity. It’s what drives us to explore the world and to learn about anything and everything. We’ve now created a Guide to Curiosity to share this skill with you. Join us across 160 thrilling, interactive pages that will draw you away from your phone and into the world. Become aware of the countless wonders and secrets hiding in plain sight and learn skills that will change how you view the world forever. Head to the shop now and join the curiosity movement – we’ve also prepared some amazing deals for you.

We Need to Rethink Exercise (Updated Version)

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신체는 칼로리로 측정되는 음식에서 에너지와 원료를 필요로 하기 때문에 체중을 감량하는 것은 어려운 일입니다.

체중을 줄이려면 섭취한 칼로리보다 더 많은 칼로리를 소모해야 하지만 운동만으로는 확실한 체중 감량 방법이 아닐 수 있습니다.

연구에 따르면 산업화된 사회와 수렵 채집 사회의 사람들은 하루에 비슷한 칼로리를 소모하며, 더 많이 움직이면 더 많은 칼로리를 소비한다는 일반적인 믿음에 도전합니다.

칼로리 소모와 체중 감소의 역설

활동적인 사람은 비활동적인 사람보다 약간 더 많은 칼로리를 소모하지만, 그 차이는 미미하며 생활 방식과 관련이 없는 경우가 많습니다.

근육량당 신체의 칼로리 예산은 안정적으로 유지되며, 무의식적인 행동과 운동에 대한 적응을 통해 지방 감소를 방해합니다.

근육량은 칼로리 소모량을 증가시키지만 체중 감량에 미치는 영향은 상대적으로 작기 때문에 체중 감량 정체기가 흔히 발생합니다.

신체는 다양한 시스템에 여분의 에너지를 사용하므로 만성 염증과 심각한 질병을 유발할 수 있습니다.

코르티솔과 같은 호르몬 생산은 과도한 에너지로 인해 증가하여 만성 스트레스 및 관련 건강 문제를 일으킵니다.

규칙적인 운동은 내부 균형을 회복하고 염증과 스트레스를 줄이며 전반적인 건강과 장수를 증진하는 데 매우 중요합니다.

인간은 굶주린 두뇌와 장기간의 유년기 의존성으로 인해 효율적인 칼로리 수확자로 진화했습니다.

이러한 독특한 적응 덕분에 유인원의 친척보다 더 많은 칼로리를 수집할 수 있었고, 조상 부족 내에서 음식을 공유하는 협력적인 시스템을 구축할 수 있었습니다.

하지만 현대 사회에서는 이러한 진화적 특성이 과식과 과잉 생산으로 이어져 비만이 만연하는 원인이 되었습니다.

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