Eat to Live为生存而食
A meager diet may give you health and long life, but it's not much fun —and it might not even be necessary. We may be able to hang on to1 most of that youthful vigor even if we don't start to diet until old age.
Stephen Spindler and his colleagues from the University of California at Riverside have found that some of an elderly mouse's liver genes can be made to behave as they did when the mouse was young simply by limiting its food for four weeks. The genetic rejuvenation won't reverse other damage caused by time for the mouse, but could help its liver metabolize drugs or get rid of toxins. 2
加州大学 Riverside 分校的斯蒂芬· 斯潘德尔及其同事发现，只要连续四周限制一些衰老的老鼠进食， 它们的肝脏基因就会变得和年轻时一样充满活力。虽然老鼠的肝部基因恢复活力不会逆转它们在其他方面的老化，但是却有助于这些老鼠的肝脏对药物的新陈代谢和清除霉素。
Spindler's team fed three mice a normal diet for their whole lives, and fed another three on half -rations.3 Three more mice were switched from the normal diet to half-feed3 for a month when they were 34 months old—equivalent to about 70 human years.
The researchers checked the activity of 11,000 genes from the mouse livers, and found that 46 changed with age in the normally fed mice. The changes were associated with things like inflammation and free radical production4—probably bad news for mouse health. In the mice that had dieted all their lives, 27 of those 46 genes continued to behave like young genes. But the most surprising finding was that the mice that only started dieting in old age also benefited from 70 percent of these gene changes.
研究者们检查了这些老鼠肝脏的 11000种基因的活性，发现正常饲养的老鼠有46中基因随年龄的改变 而改变。这些改变都有体内痰症和自由基的产生有关——这对老鼠的健康来说不是什么好消息。而对于那 些终身都在节食的老鼠来说，那46种基因中的27种仍然继续保持着青春活力。但是最令人吃惊的发现却是 那些只是在老年时期节食的老鼠们受益于仅有70%的基因改变。
“This is the first indication that these effects kick in5 pretty quickly, ”says Huber Warner from the National Institute on Aging near Washington, D. C.
No one yet knows if calorie restriction works in people as it does in mice, bus Spindler is hopeful. “There's attracting and tempting evidence out there that it will work.” he says .
If it does work in people, there might be good reasons for rejuvenating the liver. As we get older, out bodies are less efficient at metabolizing drugs, for example. A brief period of time of dieting, says Spindler, could be enough to make sure a drug is effective.
But Spindler isn't sure the trade-off is worth it. 6 “The mice get less disease, they live longer, but they're hungry,” he says. “Even seeing what a diet does, it's still hard to go to a restaurant and say： ‘I can only eat half of that.’”
但是斯潘德尔并不确定这个方法值得尝试。老鼠患病少了， 寿命延长了， 但是它们很饥饿， 他说， 即 使能清楚地认识到节食的功效，人们仍然很难在餐馆中说自己只能吃一半的食物。
Spindler hopes we soon won't need to diet at all. His company, Life Span Genetics in California, is looking for drugs that have the effects of calorie restriction.
calorie n卡 (热量的单位)
1. hang on to ： 继续保留。例如：You should hang on to that painting – it might be worth a lot of money one day. 你应该继续保留那幅画，或许有一天它会值很多钱。
2. The genetic rejuvenation won‘t reverse other damage caused by time for the mouse, but could help its liver metabolize drugs or get rid of toxins. 老鼠的肝部基因恢复活力不会逆转老鼠在其他方面的老化，但却有助于肝脏代谢药物或除去毒素。 other damage caused by time 岁月造成的其他方面的破坏，即“其他方面的老化”。metabolize drugs：代谢药物，即“使药物降解”。 get rid of：摆脱，除去。
3. half-rations 和 half-feed： 都是指“老鼠饲料正常定量(normal diet) 的一半”。
4. free radical production：指“自由基的产生”=(有机体组织、器官等的)无限激增。
5. kick in ：意为“开始起作用”。如：We‘re still waiting for the air conditioning to kick in. 我们还在等着空调开始起作用。
6. be worth it ： 意为“值得，有益”。例如：They are expensive, but they are worth it. 那些东西很贵，但很值。
1. According to the passage, which of the following is NOT true?
A. Eating less than usual might make us live longer.
B. If we go on a diet when old, we may keep healthy.
C. Dieting might not be needed.
D. We have to begin dieting from childhood.
1. D 第一段第一句讲“节食可能不是非做不可的事”， 第二句讲“即使上了年纪再节食， 我们仍然有可 能在很大程度上保持青春活力”，因此，“我们必须从小就开始节食”是错误的，D 是答案。
2. Why does the author mention an elderly mouse in paragraph 2?
A. To describe the influence of old age on mice.
B. To illustrate the effect of meager food on mice.
C. To tell us how mice‘s liver genes behave.
D. To inform us of the process of metabolizing drugs.
2. B 第二段提及“一只高龄老鼠”的时候，作者谈到，“只要连续四周限制它进食，它肝脏中的某些基因就会变得和衰老前一样充满活力”。据此，“为了描述节食对老鼠所产生的影响”最好地回答了题干中的问题。
3. What can be inferred about completely normally fed mice mentioned in the passage?
A. They will not experience free radical production.
B. They will experience more genetic rejuvenation in their lifetime.
C. They have more old liver genes to behave like young genes.
D. They are more likely to suffer from inflammation.
3. D 第四段提到，正常饲养的老鼠随着年龄的增长有46条肝脏基因会发生变化。这种变化与炎症和自由基的产生(身体组织无限激增)相关“，因此，D 正确。
4. According to the author, which of the following most interested the researchers?
A. The mice that started dieting in old age.
B. 27 of those 46 old genes that continued to behave like young genes.
C. Calorie restriction that works in people.
D. Dieting that makes sure a drug is effective.
4. A 第四段最后一个句子讲“但最惊人的发现是那些上了年纪才开始节食的老鼠也能从70% 的基因变化中受益“。”最惊人的“自然是”最令研究人员感兴趣的“。
5. According to the last two paragraphs, Spindler believes that .
A. calorie restriction is very important to young people
B.seeing the effect of a diet, people will eat less than normal.
C.dieting is not a good method to give us health and a long life.
D.drugs do not have the effects of calorie restriction.
5. C 文章的最后两段谈及 Spindler 对节食的看法。首先，他不能肯定节食是否值得。其次，他希望在不久的将来，我们不必节食。所以我们可以推知，他认为节食不是得以健康长寿的好办法。