为什么心情不好时爱吃垃圾食品

The pantheon of science includes individuals who have made enormous contributions to human health -- the likes of Pasteur and Salk. A pedestal in that temple awaits the scientist who solves the following mystery: Why do we eat junk food when we feel unloved?
在科学的万神庙里，有一些人为人类的健康做出了巨大贡献，比如巴斯德(Pasteur)和索尔克(Salk)等人。神庙里还有一个位子，正等着那位解决了这样一个迷题的科学家：为什么当我们感到没人爱的时候就会吃垃圾食品？

This isn't a silly question, certainly not during September, which happens to be National Childhood Obesity Awareness Month. There's an epidemic of obesity-related health problems, with adult-onset diabetes leading the way throughout the world. The fact that we eat when we're not actually hungry contributes a lot to this problem.
问这个问题并不愚蠢，至少在9月份时肯定不，因为这个月正好是“全国警惕儿童肥胖月”(National Childhood Obesity Awareness Month)。在世界各地，与肥胖有关的健康问题都普遍存在，成年型糖尿病尤为突出。而问题背后的一个重要原因，是我们在不饿时吃东西。

So why do we do it? It can be because everyone around us is eating. Or because food ads can be so persuasive. Or because we want to bankrupt a hated party host by eating all his Cheetos.
那我们为什么在不饿时吃东西呢？可能是周围的人都在吃，也可能是食品广告说服力太强。还有可能是我们不喜欢某场聚会的东道主，想把他的薯片吃光，吃到让他破产。

One of the best-understood examples of non-nutritive eating is the fact that stress tends to make us eat more. It makes sense psychologically, in that the people most prone to stress eating are those most actively restricting food intake the rest of the time: When the going gets tough and they need to be nice to themselves, this is how they ease up. They prefer to eat fats and carbs. If the boss is a creep, why not run wild on the chocolate-covered walrus blubber?
非营养性进食最容易理解的一个例子，是压力往往导致我们吃得更多。这可以从心理学角度解释，最容易在压力下进食的人，就是平时最积极限制进食的那些人：当处境不顺、需要善待自己的时候，进食便是他们放松的方式。他们更喜欢摄入脂肪和碳水化合物。如果老板是个混蛋，不如狂吃包巧克力的海象肉吧？

But we can't trace these habits merely to the complexities of the human psyche, because it's not just humans who exhibit them. Stress a lab rat by, let's say, putting an unknown rat in its cage, and it will eat more and show a stronger preference for high-fat/high-carb options than usual.
但我们不能把这些习惯一股脑儿地归到人类心理的复杂性上面，因为表现出这些习惯的不只是人类。给一只实验鼠施加压力（比如在它的笼子里放一只陌生老鼠），它就会吃得更多，并且比平时更加倾向于吃高脂肪、高碳水化合物的东西。

This phenomenon's occurrence in many species makes evolutionary sense. For 99% of animals, stress involves a major burst of energy use as they, say, run for their lives. Afterward, the body stimulates appetite, especially for high-density calories, to rebuild depleted energy stores. But we smart, neurotic humans keep turning the stress-response on for purely psychological reasons, putting our bodies repeatedly into the restocking mode.
这种现象出现在很多物种当中，这可以从进化论角度解释。对于99%的动物来说，压力都涉及能量消耗的大幅增加（比如说在逃命的时候）。在这之后，身体刺激食欲、特别是对高热量的食欲，以重新积累耗尽的能量储备。但聪明而又神经兮兮的人类因为纯粹心理上的原因而不断出现应激反应，使我们的身体反复进入重新积累能量的模式。

Scientists are beginning to understand how this stress-related junk-food craving works. Stress increases the release of 'endogenous opioids' in some brain regions. These neurotransmitters resemble opiates in their structure and addictive properties (and opiates work by stimulating the receptors that evolved for responding to the brain's opioids). This helps to account for the hugely reinforcing properties of junk food at such times.
科学家正在开始理解压力导致垃圾食品渴求的机理。压力会增加大脑中某些区域“内源性阿片口”的释放，而这些神经传导物质的结构和成瘾属性类似于阿片口（阿片口是通过刺激受体起作用，这些受体是为了应脑部的阿口片进化而成）。这有助于理解垃圾食品在压力时刻的巨大强化属性。

Stress also activates the 'endocannabinoid' system in the brain. Yes, there's a class of chemicals in the brain that resemble the ingredient in cannabis that famously links pot to getting the munchies. And stress activates another brain chemical called neuropeptide Y that can stimulate the craving for fat and sugar.
压力还会激活脑中的“内源性大麻素”系统。是的，大脑中有一类化学物质就像大麻中所含那种导致吸食后想吃东西的成分一样。此外，压力还会激活另一种名叫“神经口Y”的大脑化学物质，它可以激发人对脂肪和糖的欲望。

The most fundamental mechanism to explain this stress effect is that comfort food is, well, comforting. As first demonstrated by Mary Dallman and colleagues at the University of California, San Francisco, working with lab rats, fat and carbs stimulate reward systems in the brain, thereby turning off the body's hormonal stress-response.
这种压力效应背后的最基本机制，在于安慰食物真的让人感到安慰。玛丽・多尔曼(Mary Dallman)和加州大学旧金山分校(University of California, San Francisco)的同事利用实验鼠首次证明，脂肪和碳水化合物会刺激大脑中的激励机制，进而屏蔽掉身体激素的应激反应。

It may seem unlikely that one type of pleasure works to offset the effects of a very different source of displeasure. Why should fat-laced rat chow lessen angst about a new cage mate? Yet we regularly make much bigger leaps. Burdened with unrequited love? Shopping often helps. Roiled with existential despair? Bach might do the trick. The common currency of reward in the brain makes for all sorts of unlikely ports in a storm.
一种快感抵消另一种来源非常不同的不快感，看起来或许是不太可能。为什么富含脂肪的食物会减轻老鼠对新同伴的紧张感呢？然而我们人类的跳跃常常要大得多。饱受单相思之苦？大购物常会有帮助。因怀疑人生而烦恼？听巴赫或许有用。大脑中的激励机制就成了“病急”之中乱投的“医”。

But despite the varied possibilities of sources of comfort, some exert particularly strong primal pulls -- to the detriment of our health. It is a sign of our evolutionary legacy that, at the end of a stressful day, far fewer of us will seek solace in the poetry of Robert Frost than in a pint of double fudge brownie ice cream.
但是，尽管安慰的来源各种各样，有些安慰来源用力太猛，从而有害于我们的健康。它体现了一项我们在进化过程中的遗留物：在结束充满压力的一天之后，从罗伯特・弗洛斯特(Robert Frost)诗篇里寻求慰藉的人，远远少于来一斤双乳脂软糖巧克力冰激凌的人。