Do you really need to exercise to loseweight?

你真的需要锻炼来减重吗？

英文原文来源：http://health.usnews.com/wellness/articles/2016-07-22/do-you-really-need-to-exercise-to-lose-weight?int=a14709

（此英文文章只做翻译练习之用）

When most people decide to lose weight, they go on a diet.It's just automatic.

大部分人决定减肥时，他们会去通过节食的方式。基本上是一种自动的选择。

Exercising,however, tends to be a totally different story. After all, exercise takes timeout of our already over-packed schedules, gym memberships don't come cheap and,let's face it, exercise isn't the most exciting thing you can do with the sparetime you do have.

但是锻炼似乎是另一种完全不同的方式。毕竟，锻炼是要在我们本身已经超负荷的时间表里再挤出时间，健身会员卡也并不便宜。而且，让我们承认吧，健身并不是你在闲暇时的最令人激动的活动。

So we tell ourselves – and anyone who tries to force us to exerciese–"diet makes a bigger dent when it comes to weight loss, anyway."

因此我们告诉自己和那些试图强迫我们去锻炼的人：在你想要减重时，节食会是有更大的效果。

Andyou wouldn't be completely wrong.

你并不是完全没有道理。

Exercise's Weight-Loss Weakness

用锻炼方式来减重的负面效果

Weight loss boils down to calories in versus calories out. To lose weight, you have to maintain a caloric deficit, meaning that you'reconsuming fewer calories than you're burning each day.

减重归根到底是摄入的卡路里和消耗的卡路里之间的对比。为了达到减重的目的，你不得不保持一个所谓的卡路里赤字，意思是你摄入的卡路里要小于你消耗的卡路里。

And,when it comes to achieving that caloric deficit, minimizing calories in provesto be easier than maximizing calories out. "While it may take an hour toburn 500 calories by exercising, it takes just a few minutes to eat that allback," says registered dietitian and certified strength and conditioningspecialist Alissa Rumsey, spokeswoman for the Academy of Nutrition andDietetics.

为了达到这个卡路里赤字，使摄入的卡路里最小化被证明是比消耗卡路里最大化更容易达成的。“可能为了消耗掉500卡路里，你需要锻炼一个小时，只需要几分钟就吃回来了”Alissa

Rumsey说，她是注册营养师，也是通过认证的体能训练专家同时是营养与饮食结构学院的发言人。

What'smore, it may actually take more than an hour to burn those 500 calories. Whilea systematic review from Montclair State University found that the actual actof exercise burns fewer calories than we've always thought, a 2016 CurrentBiology study determined that after a certain point, exercising for longerperiods does not necessarily burn more calories.

更多的是，可能实际上要花费超过一个小时才能消耗掉500卡路里。一项Montclair州立大学的系统性研究发现，真实锻炼所消耗掉的卡洛里比我们平时预期的要低。2016年一项正在进行中的生物学研究证实达到一个限度后，锻炼时间的加长并不一定消耗掉更多的卡路里。

In the study, people who worked out moderately burned about 200 more calories per

day than sedentary folks. However, those who exercised even more did not burn as many calories per day as would be expected given their activitylevels. Researchers concluded that physical activity wasn't all that importantto weight loss.

研究中表明，温和的锻炼的人比不爱运动的人每天会多消耗200卡路里。但是，锻炼更多的人，考虑到他们锻炼的程度，他们其实并没有消耗掉与其程度预期相符的卡路里。研究人员总结说体育锻炼对于减重来说并没有那么重要。

There is, however, a huge difference between body weight and body composition. Body

weight is the number on your bathroom scale. Body composition is the percentage of that number that is fat, versus the percentage that is made up of lean tissues like muscle. And, even though we all obsess over the scale, what really determines health – or even physique for that matter – is body composition, Rumsey explains.

但是，体重和身体结构是有很大区别的。体重是你在自家体重秤上所显示的数字。身体结构则是关于身体里百分之多少是肥肉，百分之多少是肌肉。即使我们每个人都关注体重秤上的数字，但是真正决定你健康与否或者身材如何的则是你的身体结构。

It'simportant to realize that the Current Biology study controlled for both. Itdidn't investigate how exercise affects body composition. And, to be clear,when it comes to body composition, exercise rules supreme.

应该意识到现今的生物学研究对于两者都有涉及。过去不曾调查锻炼是如何影响身体结构的。要知道，如果谈到身体结构的话，锻炼则是起主要作用的。

That's because, apart from burning calories in the gym, exercise (or more specifically, the right exercise) has the potential to greatly increase your resting (or basal) metabolic rate, according to research published in Proceedings of the Nutrition Society. Resting metabolic rate is the number of calories that you burn sitting, breathing and letting your heart beat. The number of calories you burn simply by living. The study's authors note that resting metabolic rate is the single largest determiner of how many calories you burn each day. So when it comes to weight loss and improving body composition, resting metabolic rate matters. 

这是因为，根据发表在营养学社会杂志上的研究表明，除了在健身房里燃烧卡路里之外，锻炼，严格的说是正确的锻炼能够提高你的基础代谢率。基础代谢率是指你在坐着、呼吸以及心脏保持跳动所消耗掉的卡路里数量。是你保持活着的状态所需要消耗的卡路里数量。这项研究的坐着表示基础代谢率是决定你每天消耗掉多少卡路里的单一决定因素中最重要的一个。所以，当提到减重以及改善身材时，基础代谢率是很重要的影响因素。

Theauthors even shrug off the fact that the direct effects of exercise on energyexpenditure, meaning the number of calories you can burn during an exercisesession, are just a sweaty drop in the bucket of overall caloric expenditure.They basically say, "Sure, you can only burn so many calories during 30minutes of exercise. But exercise will still help you burn more calories the other23 hours and 30 minutes of the day."

作者们甚至对于锻炼对于能量消耗的直接作用满不在乎，也就是你在锻炼时所消耗掉的卡路里数量，只是众多能量消耗中的很小一点点。他们基本上说，当然，你只能在30分钟的锻炼中消耗掉这么多的卡路里。但是锻炼可以帮助你在一天中剩余的23小时零30分钟里消耗掉更多卡路里。

Exercise can increase resting metabolic rate in two ways. First, it creates what's termed excess post-exercise oxygen consumption, or EPOC, an increased caloric burn that continues even hours after you've left the gym as your body works to return to a homeostasis environment. EPOC is largely determined by the intensity of your exercise. Work closer to your max capacity, and the harder your body will have to work afterward to lower your core body temperature, repair muscle fibers, clear your body of metabolic waste and get you ready for your next exercise session. Second of all, exercise, especially strength training exercise, increases your body's levels of lean muscle, which, apart from uncontrollablefactors like your age, sex and genetics, makes the biggest impact on yourresting metabolic rate.

锻炼时在两个方面提高基础代谢率。首先，它创造了被称之为运动后过量氧耗的现象，也简称为EPOC，是一种为了使机体在运动后恢复期内偿还运动中的氧亏，以及在运动后使处于高水平代谢的机体恢复到安静水平时消耗的氧量。EPOC的大部分是由你锻炼的强度所决定的。越接近你的运动极限，你的身体越需要在运动后工作来使你的恢复到正常状态时的体温、修复肌肉过热、清楚乳酸堆积废物，为了下一次的锻炼做准备。其次，锻炼，尤其是力量训练，能够提高机体的肌肉含量。肌肉含量是除了其他不可控制的因素如年龄、性别、基因等之外决定你基础代谢率的最重要因素。

So, to connect the dots, exercise increases muscle, which increases your resting metabolic rate, which increases your daily energy expenditure, which helps you achieve a caloric deficit, which results in weight loss–even on days that you don't exercise.

所以，总结来说就是，锻炼提高肌肉含量，提高你的基础代谢率，提高你每天的能量消耗，帮助你达到一个卡路里赤字状态，结果是体重下降，即使是在你不锻炼的日子。

Exercise's ability to increase resting metabolic rate becomes even more impressive when you consider what weight loss does to your metabolism. According to the International Journal of Obesity, losing 10 percent of your body weight results in your resting metabolic rate slowing by 20 to 25 percent. Called "metabolic adaptation" or "adaptive thermogenesis," it's a byproduct of your body trying not to lose weight, which it interprets as starvation,even when it's achieved in a healthy, balanced way. (Of course, this metabolicadaptation is even worse in people who excessively cut calories, but that's awhole other story!) It also partially explains why, four to five years aftersuccessfully losing weight, about two-thirds of people actually weigh more thanthey did to begin with, according to research from the University of California– Los Angeles.

当你考虑减重对你的新陈代谢的影响的时候，锻炼能够提高基础代谢率的能力将会格外突出。根据国际肥胖日志表示，减重10%将会导致你基础代谢率减少20%至25%。这被称为新陈代谢惯性或者习惯性生热作用。这是一种你在试图减重时的副作用。它认为你的身体处于一种饥饿状态，即使你已经达到了一个健康、均衡的生活方式。这其实也能部分解释了为什么有些人在成功减重4到5年后，其中三分之二的人会比减重前更重，根据加利福尼亚大学的研究表示。

"Inorder to lose weight and keep it off in the healthiest possible way, you needto maintain lean body mass and lose only your excess fat. If you simply cutcalories, but you don't maintain a healthy level of exercise, you will lose notonly body fat, but you'll lose muscle mass as well. When you are losing bothfat and lean body mass, or muscle, you are essentially starving yourself.Starvation results in hormone imbalances, muscle wasting, loss of essentialminerals and a long list of physical problems," explains Brian Quebbemann,a metabolic and bariatric surgeon and founder of the N.E.W. Program weight-losssystem in California. "Achieving a healthy balance between body fat andmuscle requires a healthy balance between exercise and calories consumed. Byfocusing only on cutting calories, you are only looking at half theequation."

为了减重，并且以最健康的方式减重，你必须保持你的肌肉含量，只减少多余的脂肪。如果你只是简单的减少卡路里，但并没有保持一个合适的锻炼水平，你不仅减了脂肪，也减了肌肉。当你同时减少脂肪和肌肉时，其实你是在饿自己。饥饿会导致荷尔蒙水平失衡，肌肉浪费，基础矿物元素的损失以及其他很多生理上的问题。达到身体脂肪含量与肌肉含量的健康的平衡状态需要保持锻炼和摄入卡路里的均衡。如果你只关注减少卡路里，那你只看到了问题的一半。

Soyeah, you really need to exercise to lose weight. But not because exerciseactually burns that many calories.

所以，是的，你确实需要锻炼来减重。但并不是因为锻炼能够消耗掉那么多的卡路里。