Your Workout Burns Fewer Calories Than You Think

你鍛煉身體消耗的卡路里沒你想象的多

Our bodies compensate for at least a quarter of the calories we expend during exercise, undermining our best efforts to lose weight by working out.

我們的身體至少自動(dòng)補(bǔ)償了我們在運(yùn)動(dòng)中消耗的四分之一的卡路里，破壞了我們想通過運(yùn)動(dòng)減肥的最佳努力。

By Gretchen Reynolds, The New York Times, Sept. 22, 2021

作者：格雷琴·雷諾茲，紐約時(shí)報(bào)，2021年9月22日

For every 100 calories we might expect to burn as a result of working out, most of us will actually net fewer than 72 calories burned, according to an eye-opening new study of how physical activity affects our metabolisms.

根據(jù)一項(xiàng)影響我們新陳代謝的研究顯示，我們預(yù)計(jì)因鍛煉身體燃燒掉的每100卡路里中，我們中的大多數(shù)人實(shí)際燃燒的熱量將少于72卡路里。

The study finds that our bodies tend to automatically compensate for at least a quarter of the calories we expend during exercise, undermining our best efforts to drop pounds by working out. The results also show that carrying extra pounds unfortunately compounds calorie compensation, making weight loss through exercise even more elusive for those who are already overweight.

研究發(fā)現(xiàn)，我們的身體傾向于自動(dòng)補(bǔ)償我們在運(yùn)動(dòng)中消耗的至少四分之一的卡路里，這破壞了我們通過運(yùn)動(dòng)減肥的最佳努力。研究結(jié)果還表明，不幸的是，如果身體超重還會(huì)增加這一熱量補(bǔ)償，這使得那些已經(jīng)超重的人更難通過鍛煉減肥。

But the study suggests, too, that calorie compensation varies from person to person, and that learning how your metabolism responds to workouts may be key to optimizing exercise for weight control.

但研究也表明，熱量補(bǔ)償因人而異，了解你的新陳代謝對鍛煉的反應(yīng)可能是優(yōu)化鍛煉以控制體重的關(guān)鍵。

In theory — or in a kindlier, alternative universe — exercise would aid substantially in weight loss. When we move, our muscles contract, requiring more fuel than at rest, while other organs and biological systems likewise expend extra energy. Thanks to past laboratory studies, we know approximately how much energy these processes demand. Walking a mile, for instance, burns approximately 100 calories, depending on someone’s body size and walking speed.

從理論上講（或者在一個(gè)更仁慈的、有替代選擇的世界里）運(yùn)動(dòng)將大大有助于減肥。當(dāng)我們運(yùn)動(dòng)時(shí)，我們的肌肉收縮，需要比休息時(shí)更多的能量，而其他器官和生物系統(tǒng)也同樣消耗額外的能量。由于過去的實(shí)驗(yàn)室研究，我們大致知道這些過程需要多少能量。例如，步行一英里可以消耗大約100卡路里的熱量，這取決于一個(gè)人的體型和行走速度。

Until recently, most people, including exercise scientists, assumed that this process would be additive — that is, stroll a single mile, burn 100 calories. Stroll two, burn 200, and so on, in logical, mathematical fashion. If we do not then replace those calories with extra food, we should wind up burning more calories than we consume that day and start dropping pounds.

直到最近之前，包括運(yùn)動(dòng)科學(xué)家在內(nèi)的大多數(shù)人都認(rèn)為這一過程是增加性的——也就是說，散步一英里，燃燒100卡路里。以邏輯和數(shù)學(xué)的方式，漫步兩次，燃燒200次，等等。如果我們不用額外的食物來代替這些卡路里，我們?nèi)紵目防飼?huì)比當(dāng)天消耗的更多，體重也會(huì)開始下降。

But that rational outcome rarely happens. In study after study, most people who begin a new exercise program lose less weight than would be expected based on the number of calories they burn during their workouts, even if they strictly monitor their diets.

但這種理性的結(jié)果很少發(fā)生。在一項(xiàng)又一項(xiàng)的研究中，大多數(shù)開始新的鍛煉計(jì)劃的人，即使他們嚴(yán)格監(jiān)控自己的飲食，根據(jù)他們在鍛煉過程中燃燒的卡路里數(shù)量，減少的體重也比預(yù)期的要少。

So, some scientists began speculating that energy expenditure might be less elastic than we had thought. In other words, it might have limits. That possibility gained traction in 2012, with the publication of an influential study of African hunter-gatherers. It showed that, although the tribespeople regularly walked or jogged for hours, they burned about the same number of total daily calories as relatively sedentary Western men and women. Somehow, the study’s authors realized, the active tribespeople’s bodies were compensating, dialing back overall calorie burning, so that they avoided starvation as they stalked their food.

因此，一些科學(xué)家開始推測能量消耗可能沒有我們想象的那么有彈性。換句話說，它可能有局限性。這種可能性在2012年隨著一份對非洲狩獵采集者有影響的研究報(bào)告發(fā)行得到了廣泛關(guān)注。該研究表明，盡管非洲等采獵部落居民經(jīng)常步行或慢跑數(shù)小時(shí)，但他們每天消耗的總熱量和相對久坐不動(dòng)的西方男性和女性相當(dāng)。該研究的作者們意識到，不知何故，活躍部落的人們的身體在進(jìn)行補(bǔ)償，將總的熱量燃燒撥回，這樣他們就避免了在跟蹤食物時(shí)挨餓。

本公號閱讀推薦：Why you shouldn't exercise to lose weight／60+ 研究表明你不應(yīng)該通過鍛煉身體來減肥

Other small studies since have reinforced the finding that more activity does not necessarily result in greater daily calorie expenditure. But few large-scale experiments have tried to pin down just how much our bodies compensate for the calories burned while moving, since measuring metabolic activity in people is complex and expensive.

其他一些小型研究進(jìn)一步證實(shí)了這一發(fā)現(xiàn)多運(yùn)動(dòng)并不一定會(huì)導(dǎo)致更大的每日熱量消耗。但很少有大型實(shí)驗(yàn)試圖確定我們的身體在運(yùn)動(dòng)時(shí)對燃燒的卡路里的補(bǔ)償程度，因?yàn)闇y量人體的代謝活動(dòng)既復(fù)雜又昂貴。

As part of an ambitious new scientific initiative, however, dozens of researchers recently pooled their metabolic data from multiple studies involving thousands of men and women. These studies involved drinking doubly labeled water, the gold standard in metabolic research. It contains isotopes that allow researchers precisely to track how many calories someone burns throughout the day.

然而，作為一項(xiàng)雄心勃勃的新科學(xué)計(jì)劃的一部分，數(shù)十名研究人員最近匯集了來自數(shù)千名男性和女性的多項(xiàng)研究的代謝數(shù)據(jù)。這些研究包括飲用雙標(biāo)簽水，這是代謝研究的金標(biāo)準(zhǔn)。它含有同位素，使研究人員能夠精確地追蹤一個(gè)人一天中燃燒了多少卡路里。

For the new study, which was published in August in Current Biology, some of the scientists involved in the initiative set out to see what happens to our metabolisms when we move. They pulled data for 1,754 adults that included their doubly labeled water results, as well as measures of their body compositions and basal energy expenditure, which is how many calories they burn simply by being alive, even if they otherwise are inactive. Subtracting basal numbers from total energy expenditure gave the researchers an approximation of people’s energy expenditure from exercise and other movement, such as standing, walking and general fidgeting.

8月份發(fā)表在《當(dāng)代生物學(xué)》上的這項(xiàng)新研究中，參與這項(xiàng)活動(dòng)的一些科學(xué)家著手研究我們移動(dòng)時(shí)的代謝情況。他們收集了1754名成年人的數(shù)據(jù)，其中包括他們的雙標(biāo)簽飲水結(jié)果，以及他們的身體成分和基本能量消耗的測量結(jié)果，即他們僅僅活著就燃燒了多少卡路里，即使他們沒有活動(dòng)。從總能量消耗中減去基本數(shù)字，研究人員得出了人們通過鍛煉和其他運(yùn)動(dòng)（如站立、行走和一般坐立不安）所消耗能量的近似值。

Then, using statistical models, the researchers could tally whether calories burned during activity increased people’s daily energy expenditure as expected — that is, whether people burn commensurately more total daily calories when they move more. But, the researchers found, they did not tend to burn more calories. In fact, most people seemed to be burning only about 72 percent as many additional calories, on average, as would be expected, given their activity levels.

然后，利用統(tǒng)計(jì)模型，研究人員可以統(tǒng)計(jì)出在活動(dòng)中燃燒的卡路里是否如預(yù)期的那樣增加了人們的日常能量消耗——也就是說，當(dāng)人們運(yùn)動(dòng)得更多時(shí)，是否相應(yīng)地燃燒了更多的每日總卡路里。但是，研究人員發(fā)現(xiàn)，結(jié)果是人們并不傾向于燃燒更多的卡路里。事實(shí)上，考慮到他們的活動(dòng)水平，大多數(shù)人似乎平均只燃燒了72%的額外運(yùn)動(dòng)消耗卡路里。

“People appear to be energy compensating for additional calories burned through activity by at least a quarter,” said Lewis Halsey, a professor of life and health sciences at the University of Roehampton in London and one of the lead authors of the new study.

倫敦州羅漢普頓大學(xué)生命與健康科學(xué)教授Lewis Halsey和這項(xiàng)新研究的主要作者之一說：“人們對能量消耗的能量補(bǔ)償似乎至少是四分之一?！?/p>

Unexpectedly, the researchers also found that energy compensation levels increased among people with relatively high levels of body fat. They tended to compensate for 50 percent or more of the calories they burned by being active.

出乎意料的是，研究人員還發(fā)現(xiàn)，體內(nèi)脂肪含量相對較高的人的能量補(bǔ)償水平還增加了。他們通過積極運(yùn)動(dòng)后身體往往能補(bǔ)償出他們?nèi)紵?0%或更多的卡路里。

It is important to point out that the study did not look at people’s food intake. It concentrated solely on energy outlay and how our bodies seem able to offset some of the calories burned during exercise by reducing biological activity elsewhere in the body. Just how we unconsciously orchestrate this feat, though, and which internal systems could be most affected remain unclear, Dr. Halsey said. He and his colleagues speculate that immune system operations, which require considerable energy, may get dialed down somewhat. Or we could unknowingly fidget less or otherwise grow more sedentary, over all, on days we exercise. Perhaps, too, some of the inner workings of our cells may slow, reducing our bodies’ overall energy expenditure.

需要指出的是，這項(xiàng)研究并沒有關(guān)注人們的食物攝入量。它只關(guān)注能量支出以及我們的身體如何通過減少身體其他部位的生物活動(dòng)來抵消運(yùn)動(dòng)中燃燒的部分卡路里。哈爾西博士說，我們是如何無意識地策劃這一壯舉的，以及哪些內(nèi)部系統(tǒng)可能受到的影響最大，目前尚不清楚。他和他的同事推測，需要消耗相當(dāng)大能量的人體免疫系統(tǒng)操作可能會(huì)有所減弱?；蛘?，在我們鍛煉的日子里，我們會(huì)不知不覺地少那么一點(diǎn)坐立不安，或者變得更久坐不動(dòng)。也許，我們細(xì)胞的某些內(nèi)部運(yùn)作也會(huì)減慢，從而減少我們身體的整體能量消耗。

But the new science of exercise and calorie compensation is not completely discouraging. Even people whose bodies compensate for 50 percent or more of the calories they expend during physical activity will burn more calories per day than if they remain still, Dr. Halsey pointed out. A more intractable problem with using exercise for weight loss, he continued, is that exercise realistically burns few calories, period. To drop pounds, we also will have to eat less.

但是關(guān)于運(yùn)動(dòng)和熱量補(bǔ)償?shù)男驴茖W(xué)并沒有完全令人沮喪。哈爾西博士指出，即使是身體補(bǔ)償了他們在體育活動(dòng)中消耗的50%或更多熱量的人，每天也會(huì)比保持靜止燃燒更多的熱量。他繼續(xù)說，利用運(yùn)動(dòng)減肥還有一個(gè)更棘手的問題，那就是運(yùn)動(dòng)實(shí)際上消耗的卡路里很少。為了減肥，我們還必須少吃。

“Half a cookie or half a can of cola” after a half-hour walk, and you will have taken in more calories than you burned, he said, however much or little you compensate.

他說，步行半小時(shí)后“吃半塊餅干或半罐可樂”，你攝入的卡路里將超過你燃燒的卡路里，不管你補(bǔ)償?shù)哪芰渴嵌嗍巧佟?/p>