为什么压力越大，吃得越多？

We all know what makes us fat: eating more in calories than we burn off in energy. But though this is true, it doesn’t answer the more interesting question - why do we overeat in the first place?

我们都知道当体内摄入的卡路里多于身体所消耗的热量，我们就会变胖。尽管事实如此，但一个更有趣的问题却没有得到解答——一开始我们为什么要吃那么多呢？

Why do I sometimes feel compelled to eat that bit of cake or bar of chocolate although I know I am going to regret it a few minutes later?

为什么有时尽管知道会后悔，但还是控制不住自己去吃一点蛋糕或者巧克力呢？

Is it just greed - or is something else going on?

仅仅是贪心吗？还是因为其他的原因？

Although self-control is important, there is mounting evidence that stress plays a significant part in weight gain.

尽管自控很重要，但是越来越多的证据显示压力对增重会很大的影响。

Chronic stress disrupts our sleep and our blood sugar levels. This leads to increased hunger and comfort eating.

长期的压力扰乱我们的作息，还会影响我们的血糖。它会让我们的饥饿感增加，借食消愁。

And that then leads to further disrupted sleep, even higher levels of stress and even more disrupted blood sugars. In time, this can lead not only to unhealthy levels of body fat, but also to type-2 diabetes.

这会进一步扰乱人体的睡眠，使压力增大，血糖紊乱。最后，它还能引发肥胖和2型糖尿病。

To see what can happen, Dr Giles Yeo, a member of the Trust Me, I’m a Doctor team, decided, with the help of scientists from Leeds University, to put himself through a particularly stressful day.

为了一探究竟，“相信我，我是医生”团队的加尔斯杨（Giles Yeo）博士决定，在利兹大学科学家的帮助下，亲自体验充满压力的一天。

The Leeds scientists started by asking Giles to do something called the Maastricht Stress Test.

利兹大学的科学家首先让加尔斯做一项马斯特里赫特压力测试。

They put him in front of a computer and made him rapidly subtract a number, 17, from another number, 2,043. He kept making mistakes, which for someone like Giles is particularly stressful.

他们将加尔斯坐在一台电脑前用2043减17，这样一直不停地做减法。他一直在出错，这对于他而言压力十足。

Then they got him to put his hand in a bath of ice-cold water and hold it there. Before and after these tests, the Leeds team measured Giles’s blood sugar levels.

然后科学家将他的手放在冰水缸里。在这些实验前后，都对加尔斯的血糖水平进行了测量。

Our blood sugar levels rise when we eat and, in a healthy person like Giles, they quickly return to normal.

我们进食时血糖会升高。但对于加尔斯这样的正常人来说，血糖将很快便恢复正常。

But what the Leeds team found was that on the day when Giles was being deliberately stressed, his blood sugar levels took three hours to return to normal - some six times longer than on a previous, stress-free day.

但是利兹大学的科学家发现，在加尔斯压力巨大的那天，他的血糖水平花了三个小时才恢复正常，比之前没有压力的那天慢了6倍的时间。

The reason this happens is that when you are stressed, your body goes into "fight or flight" mode.

原因是当你有压力时，你的身体便会进入“战斗还是逃跑”模式。

Your body thinks it is under attack and releases glucose into your blood to provide energy for your muscles.

你的身体认为遭到外界袭击，于是便向血液释放葡萄糖为肌肉提供能量。

But if you don’t need that energy to run away from danger, then your pancreas will pump out insulin to bring those blood sugar levels back down again.

但是如果你不要这些能量来抵御危险，你的胰腺便会释放出胰岛素重新将你的血糖降下来。

These rising levels of insulin and falling blood sugars will make you hungry - which is why you crave sugary carbs when you are stressed.

胰岛素的增多和血糖的升高会让你感到饥饿，这便是当你紧张时特别想吃甜食的原因。

The same sort of thing happens when you have a bad night’s sleep.

当你睡眠质量不好时，道理是一样的。

A recent study carried out by researchers at King’s College, London found that if you sleep-deprived people they would consume, on average, an extra 385kcal per day, which is equivalent to the calories in a large muffin.

最近一项由伦敦国王学院发起的研究发现，睡眠不足的人一天平均会消耗385千卡，相当于一大块松饼所含的热量。

Children also get the munchies when they haven’t had enough sleep.

儿童睡眠不够时也会产生饥饿感。

In another recent study, researchers took a small group of three- and four-year-olds (all regular afternoon nappers) and not only deprived them of their afternoon nap, but also kept them up for about two hours past their normal bedtime

在最近的另一项研究中，研究员挑选了一组三到四岁的孩子（均有睡午觉的习惯），实验中不仅不让他们睡午觉，晚上还把他们的睡觉时间推迟两个小时。

The following day, the children ate 20% more calories than usual, particularly more sugar and carbohydrates. They were then allowed to sleep as much as they wanted.

第二天，孩子们比平常多摄入20%的卡路里，尤其是摄入了更多的糖和碳水化合物。然后让他们想睡多久睡多久。

The day after that, they still consumed 14% more calories than normal.

过了一天，他们仍比平常多消耗了14%的卡路里。

So how can you reduce daily stress?

所以你该如何减轻压力？

Here’s a breathing technique, recommended by NHS Choices, which I find effective. You will get the most benefit if you make it part of your daily routine.

NHS Choices推荐过一项呼吸技巧，我觉得很有效。如果你每天都做，会对你身体有益处。

You can do it standing, sitting or lying - whatever is the most relaxing.

不管你是站着、坐着或是躺着，任何你觉得放松的姿势都可以做。

Start by breathing in as deeply as you can, through your nose, without forcing it, to a count of five

首先尽可能的呼吸，用鼻子呼气，尽力而为，数到五。

Then, gently exhale, through your mouth, to a count of five

然后慢慢地用嘴呼气，数到五。

Keep breathing in through your nose and out through your mouth - steadily

保持用鼻子吸气用嘴巴呼气。

Keep doing this for three to five minutes

坚持做五分钟。

One of the first things I would strongly recommend is to try to get a good night’s sleep. This is easier said than done, but NHS Choices provides some useful tips.

其中我强烈建议保持充足的睡眠。这说起来容易坚持下去很难，但是NHS Choices提供了许多很有用的建议。

You could also try some well established "stress-busting" techniques - such as exercising, gardening, mindfulness or yoga.

你也可以尝试如今发展完善的减压技巧，例如锻炼、打理花园、正念或瑜伽。

When I recently tested them, with the help of Prof Angela Clow, a stress expert from the University of Westminster, the mindfulness came out on top.

安吉拉·克洛是威斯敏斯特大学的压力研究专家。最近在他的帮助下，我对这些方法进行了测试，发现其中正念的效果最好。

But a key finding of our study was you really only got benefit if you enjoyed it.

但我们研究的一个关键发现便是，只有你真正享受，它才会对你有益。

So do try different things and see which works best for you.

所以多尝试几种方式，看哪一种对你来说最有效。