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This is Scientific American — 60-Second Science. I'm Karen Hopkin.
'Tis the season...for overeating! But it's not just your lack of willpower or the omnipresent holiday treats. No, you can lay some of the blame on ghrelin. Because a new study shows that ghrelin, the hormone that makes you hungry, also makes food...and food smells...irresistibly appealing. The finding appears in the journal Cell Reports.
Ghrelin is produced in the stomach, and its levels rise before your habitual mealtimes and after you haven't eaten for an extended period. So the hormone reminds you to put something in your belly. Injecting rats with ghrelin encourages them to eat...and people who receive a dose of ghrelin grab extra helpings from the buffet.
But how does the hormone induce overindulgence? To find out, researchers at McGill University trained volunteers to associate random images with the smell of food. For example, every time they saw a tree, they might get a whiff of freshly baked bread. At the same time, some of the subjects received ghrelin; others got only saline.

The volunteers were then ushered into an fMRI machine, where the researchers watched their brains to see which parts got turned on by different images.
Seems that in subjects under the influence of ghrelin, the brain region involved in pleasure and reward lit up only when volunteers viewed the images they associated with food aromas. Their brain pleasure centers were disinterested in images that had not been paired with food smells.
Also, when participants were then asked to rate the pleasantness of the images, the ones who'd been exposed to ghrelin gave higher grades to the food-associated pictures than did folks who got no ghrelin.
So when visions of sugarplums...or the smell of apple pie...get your stomach growlin'...you can thank—or blame—your ghrelin. As you reach for a fork.
Thanks for listening for Scientific American — 60-Second Science. I'm Karen Hopkin.

参考译文

这里是科学美国人——60秒科学8~vxPJ4pj]j*-7N0。我是凯伦·霍普金|o_l&5O%DU[W^W[;9xb。
这是暴饮暴食的时节！但暴饮暴食的原因并不仅仅是因为你缺乏意志力或无处不在的节日大餐1eY;Jp.2qeh-。并不是，你可以将部分责任归咎于胃饥饿素^@u[7dV;f,rp+_~yv。因为一项新研究表明，让你感到饥饿的激素胃饥饿素还可以令食物及食物气味产生无法抗拒的吸引力[6gaUFS#T0e%oH。这项研究结果发表在《细胞报告》期刊上8LE*nxBEkQhLEhXE=)。
胃饥饿素在胃里产生，在你平时进餐前和长时间未进食之后，胃饥饿素水平会上升onom|EG|t(k。因此，这种激素会提醒你往肚子里装点东西（进食）x(1H,x]i,#G6v~iKu。给老鼠注射胃饥饿素会让老鼠想吃东西，而注入胃饥饿素的人则会在吃自助餐时拿更多食物bJHk[-n6~uv。
但是这种激素是如何引起过度饮食的呢？为了找到答案，麦吉尔大学的研究人员训练志愿者将随机图片与食物气味联系起来m_S+B_,jp9BHIv;0。例如，每次他们看到一棵树，他们可能就会闻到新鲜出炉的烤面包的味道21bp#*uR5apq+^S.RX)。同时，部分参与者会注入胃饥饿素，其他人则只注射生理盐水JmZ|A80=~&hpU。
随后，志愿者被带进核磁共振仪，研究人员用仪器观察志愿者的大脑，看不同的图片会激活大脑的哪些部位4Qobm,!w@Yhd~hYg9!C。
看起来在胃饥饿素的影响下，志愿者只有在看到他们认为与食物香味有关的图片时，他们大脑中涉及愉悦与奖励的区域才会激活hoaE1N#z3;YS。他们大脑中的愉悦中心对未与食物气味匹配的图片没有反应4Jf(xXu(h*@4)Na@。
另外，当参与者被要求对图片的愉悦程度进行评分时，与未接触胃饥饿素的人相比，那些接触胃饥饿素的人为与食物有关的图片打出了更高的分数R,d-KRB6a7#s^Yq。
因此，当看到糖果或闻到苹果派的味道让你的肚子咕咕叫时，你可以感谢或怪罪你的胃饥饿素——在你伸手拿餐具时8TqP7~PPD;[。
谢谢大家收听科学美国人——60秒科学c=(]0~APX1。我是凯伦·霍普金Fz35bdTN5BgaCLV。

译文为可可英语翻译，未经授权请勿转载！

重点讲解

重点讲解：
1. a whiff off 一阵(气味) ；
He caught a whiff of her perfume.
他闻到了她身上的一股香水味F%+-8[C55|。
2. turn on 启动；开启；
Parents can programme the machine not to turn on at certain times.
父母可以设定这台机器的程序，使它在特定时间段无法开启cp5s*@xzMdCII@il。
3. be disinterested in 不感兴趣的；不关心的；冷漠的；
Lili had clearly regained her appetite but Doran was disinterested in food.
莉莉显然已经恢复了食欲，但多兰却提不起胃口|AVW1JXdq@。
4. be exposed to 使受…的影响；使接触；
We are exposed to an overwhelming number of chemical contaminants every day in our air, water and food.
我们每天都会通过空气、水和食品接触到数量惊人的化学污染物]UkyU6L_ex!sEz3@4*3l。