If you want to lose weight, exercise doesn’t really matter. That doesn’t sound right, does it? After all, for decades we’ve been told that the way to burn off excess calories is simple: move more. Have a slice of cake? No problem, just make up for it at the gym.

如果你想减肥，运动其实并不重要。这听起来是不是有点不对劲？毕竟，几十年来我们一直被告知，燃烧多余卡路里的方法很简单：多运动。吃了一块蛋糕？没关系，去健身房补回来就行了。

But a major new study challenges that long-standing belief. Collating data on more than 4,200 people across 34 different countries, researchers found that people who exercise more don’t burn more calories than those who sit around all day.

然而，一项新的重大研究对这一长期以来的信念提出了挑战。研究人员收集了来自34个不同国家的4200多人的数据，发现运动更多的人，其卡路里消耗量并不比那些整天久坐不动的人多。

In fact, the research found that, matched pound-for-pound, a hunter-gatherer from Tanzania’s Hadza community burns about the same number of calories each day as a typical US office worker – even though the Hadza are more active in a single day than most Americans are in an entire week.

事实上，研究发现，在体重相当的情况下，坦桑尼亚哈扎部落（Hadza community）的狩猎采集者每天消耗的卡路里数量，与一名普通的美国办公室工作人员大致相同——即便哈扎部落的人一天内的活动量比大多数美国人一周的活动量还要大。

There were some small differences in calorie burn between individuals, but overall they were minimal – and only around 10 per cent could be explained by exercise.

个体之间在卡路里消耗量上存在一些细微差异，但总体而言，这些差异非常小，而且其中只有大约10%可以归因于运动。

“We previously thought that the amount of activity could change the number of calories we burn per day. But what we’ve learned over the past decade or so is that it’s not anywhere near that simple,” says Duke University evolutionary anthropologist Prof Herman Pontzer – one of the 68 scientists behind the new research.

“我们以前认为，活动量会改变我们每天消耗的卡路里数量。但杜克大学（Duke University）进化人类学家赫尔曼·庞泽教授（Prof Herman Pontzer）说，在过去十年左右的时间里，我们了解到事情远没有那么简单。”庞泽教授是这项新研究的68位科学家之一。

So, is it time we all chuck out our running shoes and cancel gym memberships? Spoiler: sadly not. While this research suggests ‘how much you move’ has very little bearing on ‘how much you weigh’, giving up on exercise isn’t the answer either.

那么，我们是不是都该扔掉跑鞋、取消健身房会员了呢？剧透一下：遗憾的是，并非如此。尽管这项研究表明“你运动多少”与“你体重多少”关系不大，但放弃运动也并非是正确的解决之道。

Metabolism myths

新陈代谢的误区

If, as the new study suggests, only a sliver of your daily calorie burn comes from exercise, what’s using up the rest? In short: everything your body does behind the scenes to keep you alive.

如果正如这项新研究指出的那样，你每天消耗的卡路里只有一小部分来自运动，那么剩下的卡路里都消耗到哪里去了呢？简而言之，就是你的身体在幕后为了维持你的生命所做的一切。

Your lungs drawing in air, your heart pumping blood, your immune system fighting infections, your gut digesting food, your brain firing with thoughts – all of these processes need energy. A lot of it. In fact, this background work, known as your basal metabolic rate (BMR), accounts for the overwhelming majority of calories you use each day.

你的肺部吸入空气，你的心脏泵送血液，你的免疫系统对抗感染，你的肠道消化食物，你的大脑进行思考——所有这些过程都需要能量，而且是大量的能量。事实上，这些维持生命的基本“幕后工作”，被称为基础代谢率（BMR），它们消耗了你每天绝大部分的卡路里。

And here’s the crucial point: the more cells and mass you have, the more energy you’ll need overall, and the larger your basal metabolic rate will be. It makes sense in theory, but the real-world results are pretty surprising.

这是一个关键点：你拥有的细胞和质量越多，你总体所需的能量就越多，你的基础代谢率也就会越高。这在理论上是说得通的，但实际结果却相当令人惊讶。

Namely, thanks to their larger size, the overweight US office worker will generally have a higher basal metabolic rate than the Hadza hunter-gatherer.

具体来说，由于体型更大，超重的美国上班族通常会比哈扎（Hadza）狩猎采集者拥有更高的基础代谢率。

“People in the developed world burn more calories every day than people in farming, foraging and traditional groups,” Pontzer says. “They burn more, because people in the developed world tend to be bigger, and being larger generally means you’re going to burn more calories.”

庞泽表示：“发达国家的人每天燃烧的卡路里比从事农耕、采集和传统生活方式的人更多。”他继续说：“他们燃烧得更多，因为发达国家的人往往体型更大，而体型更大通常意味着你会燃烧更多的卡路里。”

It all means that once you account for body size and composition, there’s “hardly any difference” in total energy use between populations around the world, says Pontzer, referring to the study.

这意味着，庞泽在提到这项研究时指出，一旦考虑到身体大小和体成分，世界各地人群的总能量消耗“几乎没有差异”。

Or, to put another way, pound-for-pound, the office worker tied to their desk will use a similar number of calories per day as somebody far more active.

换句话说，若按单位体重计算，整日伏案工作的上班族与运动量大得多的人，其每日卡路里消耗量是相似的。

The calorie equation

卡路里方程

How could it possibly be that we all burn about the same amount of energy for our body size? According to Pontzer, it’s because when we move more (or less), our bodies don’t simply burn extra calories; our metabolism adapts, conserving energy elsewhere to balance things out.

为什么我们身体大小相近的人每天消耗的能量却差不多呢？根据蓬泽的说法，这是因为当我们运动量增加（或减少）时，身体并不会简单地额外燃烧更多卡路里；我们的新陈代谢系统会做出调整，通过在其他方面节约能量来达到平衡。

Simply put, our bodies want to stay in balance (a process biologists call homeostasis). This means that, Pontzer says, if you suddenly decided to cartwheel across a meadow every morning, your body would adapt, shifting its energy resources away from some of those background tasks to accommodate your new exercise habit.

简单来说，我们的身体倾向于保持平衡（生物学家将此过程称为“稳态”）。庞泽表示，这意味着，如果你突然决定每天早上在草地上翻筋斗，你的身体会进行调整，将能量从一些“后台”任务中转移出来，以适应你新的运动习惯。

“Our bodies are able to adjust to our different lifestyles,” he explains. “If we’re more physically active, our bodies seem to adjust to spend less energy on other stuff. The total calories burned per day is not different, even though we’re more or less physically active.”

他解释说：“我们的身体能够适应我们不同的生活方式。如果我们体力活动更多，身体似乎就会调整，减少在其他方面的能量消耗。即使我们的体力活动量或多或少，每天消耗的总卡路里总量也没有区别。”

Spending fewer calories on other bodily functions may sound alarming, but Pontzer says it’s usually not something to worry about – in fact, it’s desirable.

身体的其他功能消耗更少的热量，这听起来可能令人担忧，但庞策教授表示，这通常没什么好担心的——事实上，这反而是件好事。

“Rejuggling how calories are spent is a really good thing. Most of us spend excess calories on things like background inflammation,” he says.

“重新调整卡路里消耗的方式是一件非常好的事情。我们大多数人都会将多余的卡路里花在诸如‘隐性炎症’之类的身体问题上，”他说。

By redirecting energy away from those unnecessary background processes, exercise helps the body run more efficiently – reducing inflammation and keeping us healthier overall. In this way, Pontzer says that while it might not be the key to shedding weight, it’s crucial for maintaining a healthy, balanced body.

通过将能量从那些不必要的背景运作中转移出来，运动有助于身体更有效地运转——从而减少炎症，并使我们整体更健康。庞泽说，这样一来，尽管运动可能不是减肥的关键，但它对维持一个健康、平衡的身体至关重要。

Of course, this effect only goes so far. Suddenly ramping up your activity levels can put strain on your body, causing your immune or reproductive systems to take a hit. You might find yourself getting ill more often, your libido dropping, or your periods stopping altogether.

当然，这种效果也是有限的。突然大幅增加活动量会给你的身体带来负担，导致你的免疫系统或生殖系统受到影响。你可能会发现自己更容易生病，性欲下降，或者月经完全停止。

“It’s called overtraining syndrome,” says Pontzer. “But, unless you’re a professional-level athlete, you’re probably not going to see that.”

“这被称为过度训练综合症，”庞泽说，“但是，除非你是一名专业的运动员，否则你不太可能遇到这种情况。”

The same thing happens in reverse when you suddenly stop exercising. If you give up your cartwheeling, for instance, your metabolism shifts gears – redirecting that spare energy into background processes like inflammation instead.

同样地，当你突然停止锻炼时，情况也会反过来。例如，如果你放弃了像翻筋斗（指运动）这类活动，你的新陈代谢就会‘换挡’（调整），将那些原本节省下来的能量重新分配到像炎症这样的身体内部‘后台’过程中。

“Regardless of how active you are, the body adapts dynamically to keep expenditures within a narrow range,” explains Pontzer.

“无论你有多活跃，身体都会动态地适应，以将能量消耗保持在一个狭窄的范围内。”庞泽解释道。

The foods that fuel fat

助长脂肪的食物

In short, according to Pontzer, the real factor associated with body fat percentage isn’t exercise – it’s food.

简而言之，庞策认为，与体脂百分比相关的真正因素并非运动，而是食物。

“All the weight that we carry is the calories that we ate and never burned off,” Pontzer says. “And so, if our energy expenditures aren’t different, then it must be diet.”

“我们身上所有的体重，都是我们吃进去却从未消耗掉的卡路里，”庞泽说，“因此，如果我们的能量消耗没有差异，那么问题就一定出在饮食上。”

However, the researchers found that one type of food stood out as the main culprit behind weight gain. It wasn’t how much meat or other main food groups people ate that explained differences in obesity – it was the amount of ultra-processed food in their diets.

然而，研究人员发现，有一种食物是导致体重增加的主要“罪魁祸首”。他们指出，肥胖程度的差异并非由人们摄入多少肉类或其他主要食物种类来解释，而是由他们饮食中超加工食品的量决定的。

These packaged products are made in factories, using industrial ingredients and techniques, and sold in shops. They might include supermarket bread, biscuits, sweets, snacks, colourful cereal, bottled sauces, ready meals, flavoured yoghurts – and more.

这些包装产品是在工厂里利用工业原料和技术生产的，并在商店里出售。它们可能包括超市面包、饼干、糖果、零食、五颜六色的谷物（早餐麦片）、瓶装酱料、即食餐以及风味酸奶等。

“What we saw is that, sure enough, across all these groups, the amount of ultra-processed food that these populations are eating is a good predictor of how much body fat they have,” says Pontzer.

庞泽说：“我们发现，毫无疑问，在所有这些群体中，这些人群摄入的超加工食品量，是他们体脂含量的一个很好的预测指标。”

“It’s correlational, but I think it’s very suggestive that if you eat more ultra-processed food, you’re more likely to be overweight and obese.”

“这是一种相关性，但我认为它强烈暗示，如果你吃更多的超加工食品，你就更有可能超重和肥胖。”

While the findings are compelling, it’s important to note that the researchers didn’t directly measure what participants ate. There were no food diaries, calorie logs or nutrient breakdowns for either the US office workers or the Hadza members. Instead, the team drew on population-level data from national dietary surveys and global food consumption databases to estimate participants’ typical diets.

尽管这些发现引人注目，但重要的是，研究人员没有直接测量参与者的饮食。无论是美国办公室职员还是哈扎族人，都没有提供饮食日记、卡路里记录或营养成分分析。相反，研究团队利用国家膳食调查和全球食物消费数据库的人口层面数据，来估算参与者的典型饮食。

That might sound like nitpicking, but it’s a crucial limitation. Because we can’t see the link between ultra-processed foods, body fat and energy expenditure on an individual level, we can’t be sure why ultra-processed foods may lead to obesity.

这听起来可能有点吹毛求疵，但这却是一个关键的局限。因为我们无法在个体层面上看到超加工食品、体脂和能量消耗之间的关联，我们也就无法确定为什么超加工食品会导致肥胖。

It could be that, calorie for calorie, ultra-processed foods have particularly harmful effects. Or – as Dr Adam Collins, associate professor of nutrition at the University of Surrey, argues – it might simply be that these foods make it far easier to overconsume calories.

一种可能是，以同样的卡路里含量来衡量，超加工食品具有特别有害的作用。或者——正如萨里大学（University of Surrey）营养学副教授亚当·柯林斯（Adam Collins）博士所主张的——可能仅仅是这些食物让人们更容易摄入过量卡路里。

“It’s not the ultra-processing itself,” he says. “It’s the properties of these foods that make them hyper-palatable, easy to overconsume – as well as the fact that they’re usually energy dense but not very nutritionally dense.”

他说：“问题不在于超加工本身，而是这些食物的特性，它们超级美味，很容易吃过量——并且它们通常能量密度高，但营养密度却不高。”

By definition, ultra-processed foods are designed to be as delicious as possible, which means they tend to be high in salt, fat and sugar, low in fibre and nutrients, and easy to eat quickly and in large portions.

从定义上讲，超加工食品被设计成尽可能美味，这意味着它们往往高盐、高脂肪、高糖，低纤维、低营养，并且很容易快速大量食用。

“When people say they’re going to cut out all their ultra-processed food, what happens?” says Collins. “People end up eating less. People are more mindful of what they’re eating. They end up losing weight and becoming healthier.”

柯林斯说：“当人们说要完全戒掉所有超加工食品时，会发生什么？结果是人们吃得更少了。人们对所吃的东西会更加注意。他们最终会减轻体重，变得更健康。”

He adds: “It’s not that we’ve got to cut out all ultra-processed foods, or that every ultra-processed food is bad.” Instead, we might benefit from consuming them more mindfully and in moderation.

他补充说：“这并不是说我们必须彻底戒掉所有的超加工食品，也不是说每一种超加工食品都有害。”相反，如果我们能更有意识地、适度地食用它们，可能会从中受益。

Chewing the fat

闲聊脂肪

The new study, however, isn’t without its critics – Collins among them. In particular, he argues that exercise does play more of a role in weight loss than it’s given credit for.

然而，这项新研究也并非没有批评者——柯林斯（Collins）就是其中之一。他尤其认为，运动在减肥过程中所起的作用比人们普遍认为的要大。

“It’s true that exercise might not burn off many calories directly. And tracking ‘calories in versus calories out’ – this thinking of ‘I’ll just run off that chocolate bar’ – is outdated,” he says.

“锻炼可能确实不会直接燃烧很多卡路里。而且那种‘摄入卡路里与消耗卡路里’的追踪方式——也就是‘我只要跑一跑就能消耗掉那块巧克力棒’这种想法——已经过时了，”他说。

“But exercise can help regulate appetite and change body composition, reducing body fat and increasing muscle mass.”

“但是，运动有助于调节食欲，改变身体成分，减少体脂肪并增加肌肉量。”

As Collins points out, muscle cells are more metabolically active than fat cells, meaning that building more muscle subtly raises your daily energy needs and overall calorie burn.

正如科林斯指出的那样，肌肉细胞比脂肪细胞更具代谢活性，这意味着增加肌肉会悄然提高你日常的能量需求和总热量消耗。

Pontzer agrees that exercise can change body composition, which in turn affects metabolism – but he says these are “really small, marginal changes,” and that exercise programmes relying on them for weight loss generally don’t work.

庞泽同意运动可以改变身体成分，进而影响新陈代谢——但他表示，这些变化“非常小，微不足道”，而且那些依赖这些变化来减肥的运动计划通常无效。

Collins, however, remains unconvinced. He calls Pontzer’s model “a neat idea,” but says it’s still unproven – and that long-term studies following individuals over their lifetimes are needed to truly test it.

然而，柯林斯对此仍未信服。他称庞泽的模型为“一个巧妙的构想”，但认为它仍未得到证实——并且需要对个体进行终生追踪的长期研究才能真正验证其有效性。

Why you still need exercise

为什么我们仍然需要锻炼

Despite disagreements over how effective exercise is for fat loss, one thing everyone agrees on is that it’s incredibly good for us. It strengthens the heart, protects bones, keeps metabolism in check and boosts mental wellbeing – helping us live longer, healthier lives.

尽管大家对于运动在减脂方面的效果存在争议，但有一点是大家公认的：运动对我们的身体非常有益。它能强健心脏，保护骨骼，维持新陈代谢平衡，并提升心理健康——从而帮助我们拥有更长寿、更健康的生活。

Pontzer is hoping that health advice about weight will change – but he’s not advocating that people abandon exercise.

庞泽希望关于体重的健康建议能有所改变——但他并不主张人们放弃锻炼。

“Rather than blaming both diet and physical activity equally, which is how it’s all framed right now, I hope that we can focus entirely on diet for the obesity crisis, because that seems to be the main driver here,” he says.

他表示，“与其像现在这样，把肥胖问题同样归咎于饮食和体育活动，我希望我们能将重点完全放在饮食上，以应对肥胖危机，因为这似乎才是主要原因所在。”

“It doesn’t mean that we should stop exercising or stop telling people to exercise. Those are important goals as well – but we really need to focus our efforts on diet.”

“这并不意味着我们应该停止锻炼，或者停止建议人们锻炼。这些同样是重要的目标——但我们真的需要将精力集中在饮食上。”