U.S. researchers said Tuesday that they have identified an enzyme that may play a central role in the development of obesity in mid-life.

本周二，美國研究者表示稱，他們發(fā)現(xiàn)了一種可能在中年人發(fā)福現(xiàn)象中起到核心作用的酶。

In two groups of mice being fed high-fat foods， those who received an inhibitor that blocked the enzyme had a 40 percent decrease in weight gain compared with those that did not receive the drug.

在兩組喂食高脂肪食物的小白鼠中，一組被使用了阻斷這種酶的抑制劑，結(jié)果發(fā)現(xiàn)相比于另一組沒有用藥的小白鼠，這組小白鼠體重增加量要少40%。

The findings， published in the U.S. journal Cell Metabolism， could upend current notions about why people gain weight as they age， and could one day lead to more effective weight-loss medications.

該研究結(jié)果刊載于美國雜志《細(xì)胞新陳代謝（Cell Metabolism）》，可能會顛覆人們對于隨著年齡增長身體發(fā)福這一現(xiàn)象的認(rèn)知，或許有一天能夠幫助研制出更有效的減肥藥。

\"Our society attributes the weight gain and lack of exercise at mid-life （approximately 30 to 60 years） primarily to poor lifestyle choices and lack of will power， but this study shows that there is a genetic program driven by an overactive enzyme that promotes weight gain and loss of exercise capacity at mid-life，\" said lead study author Jay H. Chung， head of the Laboratory of Obesity and Aging Research at the National Heart， Lung， and Blood Institute （NHLBI）， part of the U.S. National Institutes of Health.

杰伊·常是這項研究的主要作者，他是美國心肺血液研究所（該研究所是美國國家衛(wèi)生研究院的一部分）下屬肥胖和衰老研究室主任，他說道：“我們社會一般認(rèn)為中年人（30到60歲）體重增加和缺乏鍛煉是因為不良的生活方式和缺乏意志力的原因，但是這項研究表明也存在著遺傳因素——一種過度活躍的酶會使得人們中年時體重增加、喪失運(yùn)動能力?！?/p>

Researchers have known for years that losing weight and maintaining the capacity to exercise tend to get harder beginning between ages 30 to 40 -- the start of mid-life.

多年來研究人員發(fā)現(xiàn)，在剛步入中年時（30到40歲）減肥和保持運(yùn)動能力往往會變得越來越困難。

In fact， it’s estimated that an average adult in America gains 30 pounds （13.6 kilograms） from age 20 to 50， even though food intake usually decreases during this period.

事實上據(jù)估計，美國成年人在20到50歲期間會平均增重30磅（約合13.6公斤）——即使這一年齡段人的進(jìn)食量通常會減少。

Scientists have developed new therapies for obesity， including fat-fighting pills， but many of those therapies have failed.

科學(xué)家們也已經(jīng)開發(fā)出了治療肥胖的新方法，包括減肥藥，但是許多治療方法都失敗了。

Chung and his associates searched for biochemical changes that occurred in middle-aged animals that are equivalent to 45 years in humans.

Chung和他的同事們在中年動物（相當(dāng)于45歲的人類）的身體上尋找生物學(xué)變化。

They found that an enzyme called DNA-dependent protein kinase， or DNA-PK， increases in activity with age.

他們發(fā)現(xiàn)隨著年齡的增長，一種被稱之為DNA依賴蛋白激酶（DNA-dependent protein kinase）的物質(zhì)活性與日俱增。

Further work showed that DNA-PK promotes conversion of nutrients to fat and decreases the number of mitochondria， tiny organelles in the cells that turn fat into energy to fuel the body.

進(jìn)一步的研究發(fā)現(xiàn)，DNA依賴蛋白激酶會促進(jìn)營養(yǎng)物質(zhì)轉(zhuǎn)化為脂肪，并且減少線粒體的數(shù)量——而線粒體是將脂肪轉(zhuǎn)化為能量以供應(yīng)人體的細(xì)胞器。

Mitochondria can be found in abundance among young people， but the numbers drop considerably in older people.

年輕人體內(nèi)存在著大量線粒體，但是老年人體內(nèi)線粒體的數(shù)量卻大幅下降。

Researchers know that decreased mitochondria can promote obesity as well as loss of exercise capacity.

研究人員發(fā)現(xiàn)，線粒體數(shù)量的減少會促進(jìn)肥胖、并且導(dǎo)致運(yùn)動能力喪失。