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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.
有很多理論可以解釋為什么節食不起作用、為什么體重降不下來或迅速反彈：節食讓你疲憊不堪；節食會消耗掉你健康的肌肉；節食是不自然的方法而且不可能終生如此而行；節食可能有害于健康而且缺少重要的營養；節食會導致飲食紊亂。
紅色標記的腦細胞對于影響食欲的荷爾蒙激素十分敏感。
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.)
但是現在來自愛因斯坦醫學院的一群研究人員有了一項新的發現——節食會導致大腦自食。（他們的這項理論發表于今日（譯注：2011.8.2）的《細胞新陳代謝》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.
科學家們已經知曉當人體開始“餓求”食物時，細胞就會開始一點一點地吞噬自己。這個過程叫做“自我吞噬”，而且這個過程是細胞生命周期常態的一部分；其它細胞在“困難時期”就是這么獲取能量的。但是人們一直以為，大腦在這些情況中是可以大體抵抗自噬的。
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.
現在看來，至少大腦的一部分——即下丘腦，是在自我蠶食，它位于腦干上方，管理著人體許多的功能，包括睡眠、體溫、口渴和饑餓。研究人員對小鼠進行研究后發現，在不喂食小鼠時，小鼠下丘腦中的神經元會吞噬其自身的細胞器和蛋白質。然后，其會引發一系列動作，包括釋放脂肪酸——其會釋放饑餓信號告訴大腦需要更多的食物。
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.
當研究人員阻斷自噬過程后，那些饑餓信號也被阻斷了。被剝奪食物之后的小鼠變得越來越輕、越來越瘦，它們吃得越來越少、消耗掉更多能量。科學家們寫道，這項新陳代謝的認知可能會促進對肥胖癥和新陳代謝癥候群更好治療的發展。
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，研究人員還推斷，該發現或許可以對解釋“為何高脂肪飲食可能會讓人更加饑餓——血液中的所有那些脂肪酸可能會引起同神經元自噬所引起的一樣的系列動作，讓人感覺更餓并提示人吃得更多”提供線索。
原文鏈接：Dieting May Cause The Brain to Eat Itself
