Why ExerciseAlone May Not Be the Key to Weight Loss

加强运动也许并不能减肥
Why ExerciseAlone May Not Be the Key to Weight Loss
If you give a mouse a running wheel, it will run.
如果给小鼠一个转轮，它就会跑起来。
But it may not burn many additional calories, because it will also start to move differently when it is
not on the wheel, according to an interesting new study of the behaviors and metabolisms of
exercising mice.
但它可能不会燃烧太多额外的热量，一项有趣的新研究对锻炼的小鼠的行为与新陈代谢进行了
研究，发现不在转轮上的时候，小鼠的行为也会开始改变。
The study, published in Diabetes, involved animals, but it could have cautionary implications for
people who start exercising in the hopes of losing weight.
发表在《糖尿病》(Diabetes)上的这项研究是关于动物的，但对于抱着减肥的希望开始锻炼的
人，它可能也有警示意义。
In recent years, study after study examining exercise and weight loss among people and animals has
concluded that, by itself, exercise is not an effective way to drop pounds.
近年来，一项又一项研究以人和动物的锻炼与减肥为内容，它们断定运动本身并不是一种有效
的减肥方式。
In most of these experiments, the participants lost far less weight than would have been expected,
mathematically, given how many additional calories they were burning with their workouts.
在其中大部分实验中，考虑到锻炼中燃烧的大量额外热量，参与者减掉的体重从数字上来说远
低于预期。
Scientists involved in this research have suspected and sometimes shown that exercisers, whatever
their species, tend to become hungrier and consume more calories after physical activity. They also
may grow more sedentary outside of exercise sessions. Together or separately, these changes could
compensate for the extra energy used during exercise, meaning that, over all, energy expenditure
doesn’t change and a person’s or rodent’s weight remains stubbornly the same.
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参与这些研究的科学家怀疑——有时也会证明——无论是人还是动物，锻炼之后往往会变得更
加饥饿，从而摄入更多热量。在锻炼之外的时间里，他们可能还会变得更喜欢久坐。这些变化
单独或加起来都可能弥补锻炼期间消耗的额外热量。这意味着总的来说，能量消耗没有变，人
或啮齿类动物的体重保持不变。
Proving that possibility has been daunting, though, in part because it is difficult to quantify every
physical movement someone or something makes, and how their movements do or do not change
after exercise. Mice, for instance, skitter, dart, freeze, groom, eat, roam, defecate and otherwise flit
about in frequent fits and starts.
但是要证明这种可能性却令人生畏。这在一定程度上是因为，人或动物的每一个动作、以及这
些动作在锻炼后的变化情况是难以量化的。比如，小鼠会蹿跳、猛冲、发呆、梳毛、进食、闲
逛、排便或断断续续地四处走动。
But recently, animal researchers hit upon the idea of using infrared light beams to track how animals
move at any given moment in their cages. Sophisticated software then can use that information to
map daily patterns of physical activity, showing, second-by-second, when, where and for how long
an animal roams, sits, runs or otherwise spends its time.
但最近，以动物为对象的研究人员想到了一个办法，用红外线光束追踪笼子里的动物在任意时
刻的活动情况。然后，复杂的软件可利用这些信息绘制出一天的身体活动模式，一秒一秒地显
示一只动物什么时候，在哪里逛、坐、跑了多久，或用其他方式度过了多长时间。
Intrigued, scientists at Vanderbilt University and other institutions thought that this technology would
be ideal for tracking mice before and after they started exercising, especially if the technology were
used in specialized metabolic-chamber cages that can quantify how much energy an inhabitant is
expending throughout the day.
范德比尔特大学(Vanderbilt University)等机构的科学家们对此很感兴趣，他们认为，这项技术
非常适合对小鼠锻炼前后的情况进行跟踪，尤其是用在专门的代谢室笼子里时——这种笼子可
以量化栖息其中的一只动物一天内消耗的能量。
So the scientists fitted out cages, added locked running wheels, and let young, healthy,
normal-weight, male mice loose in them to roam and explore for four days, providing the researchers
with baseline data about each mouse’s metabolism and natural peripatetic-ness.
所以，科学家们安好笼子，加装了锁住的跑步轮，让年轻、健康、正常体重的雄性小鼠在笼子
里自由漫步探索四天，为研究人员提供每只小鼠的新陈代谢和自然漫步的基础数据。
The wheels then were unlocked and for nine days, the mice could run at will, while also eating and
moving around off the wheels as much as they chose.
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然后，这些轮子被解开了 9 天，小鼠可以在轮子上自由玩耍，也可以随心所欲地吃东西，在轮
子周围活动。
The mice, which seem to enjoy running, hopped readily on the wheels and ran, off and on, for hours.
小鼠们似乎很喜欢在轮子上跑跳，或者从轮子上跳上跳下，持续数小时。
They showed a subsequent spike in their daily energy expenditure, according to the metabolic
measures, which makes sense, since they had added exercise to their lives.
根据新陈代谢数据，它们的日常能量消耗随之激增，这是合理的，因为它们的锻炼量增加了。
But they did not change their eating habits. Although they were burning more calories, they did not
gorge on more chow.
但它们的饮食习惯并没有改变。它们虽然燃烧了更多的热量，却没有吃掉更多的食物。
They did, however, alter how they moved. Almost immediately after they started using the wheels,
they stopped roaming around their cages as they had before the wheels were unlocked.
不过，它们的活动方式的确改变了。几乎从它们在轮子上跑步开始，它们就不再像轮子被锁着
时那样在笼子里漫步了。
In particular, they stopped engaging in the kind of lengthy meanders that had been common before
they began to run. Instead, they now usually jogged on their wheels for a few minutes, hopped off,
rested or roamed in short spurts, and then climbed back on the wheels, ran, rested, briefly roamed,
and repeated.
尤其是，它们停止了跑步前常见的漫长的散步活动。相反，它们现在通常在轮子上慢跑几分钟，
跳下来，休息或者短时间散步一会儿，然后爬回轮子，跑，休息，短时散步，如此循环。
These changes in how they spent their time neatly managed to almost counteract the extra calorie
costs from running, says Daniel Lark, a research fellow in molecular physiology at the Vanderbilt
University School of Medicine, who led the new study.
这项新研究的负责人、范德比尔特大学医学院的分子生理学研究员丹尼尔·拉克(Daniel Lark)
表示，它们在时间安排上的改变几乎抵消了跑步带来的额外热量消耗。
In general, the running mice showed a slightly negative energy balance, meaning that they were
burning a few more calories over the course of the day than they were taking in by chowing down.
总的来说，跑步的小鼠表现出轻微的能量负平衡，也就是说，它们一天中燃烧的热量比它们通
过进食摄入的能量要多一点。
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But that caloric deficit would have been about 45 percent greater, the metabolic calculations showed,
if they had not also begun moving around their cages less.
但新陈代谢数据显示，如果它们没有减少在笼中的散步，那么，热量赤字会增加约 45%。
What prompted the running mice to roam less is still uncertain.
促使跑步的小鼠减少散步的原因尚不确定。
“But it does not seem to have been fatigue or lack of time,” Dr. Lark says.
“它们似乎并没有表现出疲劳，也不是没有时间，”拉克博士说。
Wheel running is not arduous for mice, he points out, and did not fill their waking hours.
他指出，对小鼠来说，在轮子上跑并不费力，也没有占满它们醒着的所有时间。
Instead, he says, it is likely that the animals’ bodies and brains sensed the beginnings of an energy
deficit when the mice began to run and sent out biological signals that somehow advised the animals
to slow down, conserve energy, maintain homeostasis and not drop weight.
他表示，小鼠的身体和大脑很可能意识到，开始跑步后会出现能量赤字，所以发出了生物信号，
通过某种方式建议动物放慢速度，保存能量，保持内环境平衡，不要导致体重下降。
He and his colleagues would like, in future experiments, to explore how, physiologically, the
rodents’ bodies sensed the changes in their energy balance and at what point they might begin to eat
more. They also would like to study female, older and obese animals.
他和同事们想在将来的实验中探索啮齿类动物的身体是如何从生理上感知到能量平衡变化，以
及从何时起开始吃得更多。他们也想研究雌性、年老和肥胖的动物。
Mice will never be people, of course, so we cannot say whether the results of this and any follow-up
experiments would directly apply to us, Dr. Lark says.
拉克博士表示，当然，小鼠跟人类永远不一样，所以我们无法确定这项试验和后续试验的结果
是否可以直接适用于人类。
But the results do intimate that if we hope to exercise off excess pounds, we watch what we eat and
try not to move less while we work out more.
但这些研究结果表明，如果我们希望通过运动减掉多余的体重，就应该关注自己的饮食，而且
不要在增加锻炼的同时减少其他身体活动。