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There are plenty of theories for why diets don’t work, why the pounds won’t go away or they come back so quickly: Diets make you tired. They eat away at healthy muscle. They’re unnatural and can’t be followed for a lifetime. They may be unhealthy and lacking in vital nutrients. They can lead to eating disorders.
有很多理论可以解释为什么节食不起作用、为什么体重降不下来或迅速反弹：节食让你疲惫不堪；节食会消耗掉你健康的肌肉；节食是不自然的方法而且不可能终生如此而行；节食可能有害于健康而且缺少重要的营养；节食会导致饮食紊乱。
红色标记的脑细胞对于影响食欲的荷尔蒙激素十分敏感。
But now a group of researchers from Albert Einstein College of Medicine have a new theory—dieting causes the brain to eat itself. (Their study is published today in Cell Metabolism.)
但是现在来自爱因斯坦医学院的一群研究人员有了一项新的发现——节食会导致大脑自食。（他们的这项理论发表于今日（译注：2011.8.2）的《细胞新陈代谢》上。）
Scientists have known for a while that when a body becomes starved for sustenance, cells start eating bits and pieces of themselves. It’s a process known as “autophagy” and one that’s a normal part of the cell life cycle; it’s how other cells get energy during the tough times. But it was thought that the brain was largely resistant to autophagy under these conditions.
科学家们已经知晓当人体开始“饿求”食物时，细胞就会开始一点一点地吞噬自己。这个过程叫做“自我吞噬”，而且这个过程是细胞生命周期常态的一部分；其它细胞在“困难时期”就是这么获取能量的。但是人们一直以为，大脑在这些情况中是可以大体抵抗自噬的。
At least one part of the brain, however, now appears to self-cannibalize. It’s the hypothalamus, which sits right above the brain stem and regulates a variety of functions, including sleep, body temperature, thirst and hunger. The researchers, working with mice, found that neurons in the hypothalamus started eating their own organelles and proteins when the animals were deprived of food. That autophagy then set off a series of steps, which included releasing fatty acids, that resulted in the release of hunger signals, telling the brain that more food was needed.
现在看来，至少大脑的一部分——即下丘脑，是在自我蚕食，它位于脑干上方，管理着人体许多的功能，包括睡眠、体温、口渴和饥饿。研究人员对小鼠进行研究后发现，在不喂食小鼠时，小鼠下丘脑中的神经元会吞噬其自身的细胞器和蛋白质。然后，其会引发一系列动作，包括释放脂肪酸——其会释放饥饿信号告诉大脑需要更多的食物。
When the autophagy was blocked by the researchers, though, those hunger signals were blocked. The mice became lighter and leaner after being deprived of food, and they ate less and burned more energy. This insight into metabolism may lead to the development of better treatments for obesity and metabolic syndrome, the scientists write.
当研究人员阻断自噬过程后，那些饥饿信号也被阻断了。被剥夺食物之后的小鼠变得越来越轻、越来越瘦，它们吃得越来越少、消耗掉更多能量。科学家们写道，这项新陈代谢的认知可能会促进对肥胖症和新陈代谢症候群更好治疗的发展。
In addition, the researchers speculate, the finding may provide clues about why a high-fat diet may make you more hungry—all those fatty acids in the bloodstream may set off that same series of steps that the autophagy of neurons did, making a person more hungry and prompting them to eat even more.
此外，研究人员还推断，该发现或许可以对解释“为何高脂肪饮食可能会让人更加饥饿——血液中的所有那些脂肪酸可能会引起同神经元自噬所引起的一样的系列动作，让人感觉更饿并提示人吃得更多”提供线索。
原文链接： Dieting May Cause The Brain to Eat Itself
