科学家发现：垃圾食品会让你变胖 、变得懒惰甚至改变你的大脑

 Junk food makes you lazy not just fat, study suggests

　

 

一项新的研究发现，吃太多的垃圾食品不仅会让你变胖，还会让你的思维变得迟钝或缺乏动力。至少在实验鼠身上是这样的。

　

 图示：左边的大鼠吃垃圾食品 右边的大鼠吃健康食品

　

这项研究发表在《生理学与行为》杂志上，加州大学洛杉矶分校的研究人员对大鼠进行了两种不同的饮食。有一半的大鼠吃了健康的未加工食品，如玉米和鱼粉。剩下的一半被给予高糖，高度加工的饮食，类似于人类食用的垃圾食品。

 

在三个月内，研究人员观察到两组大鼠之间的显著差异。大多数情况下，他们发现吃垃圾食品的大鼠比健康饮食的老鼠要胖得多。但是不健康的大鼠也没有那么积极，这表明不良的饮食对他们的大脑有严重的影响。

　

　

图示：动物实验结果表明，不良的饮食对老鼠的大脑有严重的影响。

　

 

当研究人员让大鼠完成某些任务时，差异变得更加明显。所有的大鼠都被要求按一个杠杆来奖励食物和水。那些吃垃圾食品的大鼠对任务的反应比较慢，尽管这个奖励系统很清楚，他们知道执行任务会给他们提供更多的食物和水。不健康饮食的大鼠的平均休息时间为10分钟左右，而健康的大鼠的休息时间为5分钟左右。

　

　

　

在6个月的时间里，研究人员改变了两组大鼠的饮食习惯，给胖大鼠健康的饮食和瘦大鼠的不健康饮食。超重的大鼠吃了9天的健康食物。然而，饮食的改变并没有帮助那些不健康的大鼠减肥或者提高他们的工作能力。同样地，健康的大鼠在不健康的饮食上没有变得更胖，也没有变得更缺乏动力去完成某些任务。

 

此外，不健康饮食的大鼠被发现在他们的身体中有大量的肿瘤，而健康的大鼠的肿瘤更小，更少。

 

加州大学洛杉矶分校大脑研究所的心理学教授、首席研究员亚伦·布莱斯德尔(Aaron Blaisdell)说，体重和行为上的差异可能表明，垃圾食品在化学上改变了大脑。

　

图示：垃圾食品在化学上改变了大脑。

　

 

Blaisdell在新闻发布会上说:“超重的人经常被指责为懒惰和缺乏纪律。”“我们把我们的研究结果解释为，媒体普遍认为人们变胖是因为他们懒惰，这是错误的。”我们的数据表明，饮食引起的肥胖是懒惰的原因，而不是 结果。要么是高加工的饮食导致疲劳，要么是饮食导致肥胖，导致疲惫。

　

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Junk food makes you lazy not just fat, study suggests

 

The rat on the left ate a junk food diet; the one on the right ate healthy diet.

 AARON BLAISDELL

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A new study finds eating too much junk food doesn't only make you fat, it may also make you mentally slower or less motivated. At least that seems to be true in lab rats.

 

For the study, published in the journal Physiology and Behavior, researchers at the University of California Los Angeles put rats on two different diets. Half of the rodents ate a healthy diet of unprocessed foods, such as ground corn and fish meal. The remaining half were given a high sugar, highly processed diet, similar to the junk food humans consume.

 

Within three months, the researchers observed remarkable differences between the two groups of rats. Mostly, they found the rats on the junk food diet were significantly fatter than the rats on a healthy diet. But the unhealthy rats were also less motivated, indicating that a poor diet had a serious impact on their tiny rodent brains.

 

When the researchers put the rats through certain tasks the differences become even more apparent. All of the rats were required to press a lever for a reward of food and water. The rats on the junk food diet were slower to act on the task, even though this reward system was clearly laid out and they knew performing the task would provide them with more food and water. The rats on the unhealthy diet took breaks that averaged around 10 minutes long, versus the healthy rats whose breaks lasted for about five minutes each.

 

At the 6-month mark, the researchers switched the diets for the two groups of rats, giving the fat rats a healthy diet and the lean rats an unhealthy diet. The overweight rats ate a healthy diet for nine days. However, the change in diet didn't help the unhealthy rats lose weight or improve their ability to perform tasks. Similarly the healthy rats didn't get fatter on the unhealthy diet and didn't become less motivated to fulfill certain tasks.

 

Additionally, the rats on the unhealthy diets were found to have a large number of tumors throughout their bodies, while the healthy rats had much smaller and fewer tumors.

 

Aaron Blaisdell, a professor of the psychology at UCLA's Brain Research Institute and lead researcher, says the weight and behavioral differences may indicate that junk food chemically changes the brain.

 

"Overweight people often get stigmatized as lazy and lacking discipline," Blaisdell said in a press release. "We interpret our results as suggesting that the idea commonly portrayed in the media that people become fat because they are lazy is wrong. Our data suggest that diet-induced obesity is a cause, rather than an effect, of laziness. Either the highly processed diet causes fatigue or the diet causes obesity, which causes fatigue."

 

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