【英语时差8,16】限制饮食热量是年轻人的源泉？

Members of the Calorie Restriction¹ Society call themselves CRONies. They believe they can add years to their lives by eating 1800 calories per day. But is cutting calories the key to a long life, or just another fad²? Studies on mice and rats, give CRONies some scientific evidence to back their claims. Rodents³ given thirty to fifty percent less food live up to fifty-percent longer. But no one knew if the diet had the same effect on humans until recently. Researchers believe that animals on restricted diets live longer because of an insulin-like growth factor called IGF-1 that's made in the liver. As food intake⁴ goes down in rodents, so does the blood level of IGF-1. So, one way to figure out if humans are benefiting from the diet is by measuring their IGF-1. Scientists did just that. They took blood samples from CR Society members and compared them to people on different diets. They found that CRONies didn't have lower IGF-1 levels. As a matter of fact, vegans who were heavier and had more body fat than CRONies, had the lowest levels of IGF-1. Puzzled, scientists looked at the nutrient⁵ that was low in the vegan diet--protein. Six CRONies agreed to decrease the protein in their diet and after three weeks their IGF-1 levels dropped dramatically. This suggested that it might be lower protein intake and not fewer calories that extends life spans. The final word is still out on calorie restricted diets. Longevity⁶ may come not from fewer calories, but from eating less protein. More research is needed.

1 restriction   

n.限制，约束

参考例句：

• The park is open to the public without restriction.这个公园对公众开放，没有任何限制。
• The 30 mph speed restriction applies in all built-up areas.每小时限速30英里适用于所有建筑物聚集区。

2 fad   

n.时尚；一时流行的狂热；一时的爱好

参考例句：

• His interest in photography is only a passing fad.他对摄影的兴趣只是一时的爱好罢了。
• A hot business opportunity is based on a long-term trend not a short-lived fad.一个热门的商机指的是长期的趋势而非一时的流行。

3 rodents   

n.啮齿目动物( rodent的名词复数 )

参考例句：

• Rodents carry diseases and are generally regarded as pests. 啮齿目动物传播疾病，常被当作害虫对待。 来自《简明英汉词典》
• Some wild rodents in Africa also harbor the virus. 在非洲，有些野生啮齿动物也是储毒者。 来自辞典例句

4 intake   

n.吸入，纳入；进气口，入口

参考例句：

• Reduce your salt intake.减少盐的摄入量。
• There was a horrified intake of breath from every child.所有的孩子都害怕地倒抽了一口凉气。

5 nutrient   

adj.营养的，滋养的；n.营养物，营养品

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。

6 longevity   

n.长命；长寿

参考例句：

• Good habits promote longevity.良好的习惯能增长寿命。
• Human longevity runs in families.人类的长寿具有家族遗传性。