討厭腰中贅肉? 做家務能練出纖纖細腰大綱

One reason so many American women are overweight may be that we are vacuuming and doing laundry less often, according to a new study that, while scrupulously even-handed, is likely to stir controversy and emotions.

一項新的研究顯示，美國有如此之多的超重女性，原因之一是她們不再那麼經常使用吸塵器和洗衣服。即使以謹慎而公正的方式進行，這項研究也可能在輿論和情感層面引起軒然大波。

The study, published this month in PLoS One, is a follow-up to an influential 2011 report which used data from the U.S. Bureau of Labor Statistics to determine that, during the past 50 years, most American workers began sitting down on the job. Physical activity at work, such as walking or lifting, almost vanished, according to the data, with workers now spending most of their time seated before a computer or talking on the phone. Consequently, the authors found, the average American worker was burning almost 150 fewer calories daily at work than his or her employed parents had, a change that had materially contributed to the rise in obesity during the same time frame, especially among men, the authors concluded.

上述研究成果是2011年發表的一篇論文的續作，刊登在本月的科研雜誌《PLoS One》上。前作引起了很大反響，它通過美國勞工統計局(Bureau of Labor Statistics)的數據得出結論說，50年來，大多數美國勞動者逐漸開始坐着工作。像四處走動或搬運東西這樣的體力勞動幾乎已經消失。這些數據顯示，現在勞動者把大多數時間都用在了操作電腦和打電話上。該論文的作者發現，和他們的父輩相比，美國勞動者每天在工作中消耗的熱量減少了150大卡。作者斷定，這樣的變化對同一時期肥胖現象的增多有實質性的推動作用，特別是男性肥胖。

“Fifty years ago, a majority of women did not work outside of the home, ” said Edward Archer, a research fellow with the Arnold School of Public Health at the University of South Carolina in Columbia, and lead author of the new study.

哥倫比亞市南卡羅來那大學阿諾德公共健康學院(Arnold School of Public Health at University of South Carolina)研究員愛德華·阿徹(Edward Archer)博士是這篇新研究報告的主筆。他說：“50年前，多數女性都不外出工作。”

So, in collaboration with many of the authors of the earlier study of occupational physical activity, Dr. Archer set out to find data about how women had once spent their hours at home and whether and how their patterns of movement had changed over the years.

因此，阿徹博士聯合了在之前的論文中探討過職業體力勞動情況的多位作者，開始着手尋找過去女性在家中分配時間的數據，進而探究這些年來她們的行爲模式是否改變以及出現了哪些變化。

He found the information he needed in the American Heritage Time Use Study, a remarkable archive of “time-use diaries” provided by thousands of women beginning in 1965. Because Dr. Archer wished to examine how women in a variety of circumstances spent their time around the house, he gathered diaries from both working and non-employed women, starting with those in 1965 and extending through 2010.

他在一項名爲“美國時間分配研究資料庫”(American Heritage Time Use Study, AHTUS)的研究中找到了自己需要的信息。AHTUS的課題是美國人怎樣利用時間，它有一個非同凡響的數據庫，其中收集了從1965年至今數千名美國女性的日記，內容是自己如何分配時間。由於阿徹博士希望瞭解不同條件下美國女性怎樣在家裏支配時間，所以他同時收集了職業女性和家庭主婦的日記，這些日記從1965年開始，一直延續到2010年。

He and his colleagues then pulled data from the diaries about how many hours the women were spending in various activities, how many calories they likely were expending in each of those tasks, and how the activities and associated energy expenditures changed over the years.

接下來，阿徹博士和同事們開始從這些日記中提取信息，以確定美國女性在各項家務上花費的時間、消耗的熱量以及這麼多年來這些家務和與之相關的能量消耗有了怎樣的變化。

As it turned out, their findings broadly echoed those of the occupational time-use study. Women, they found, once had been quite physically active around the house, spending, in 1965, an average of 25.7 hours a week cleaning, cooking and doing laundry. Those activities, whatever their social freight, required the expenditure of considerable energy. (The authors did not include child care time in their calculations, since the women’s diary entries related to child care were inconsistent and often overlapped those of other activities.) In general at that time, working women devoted somewhat fewer hours to housework, while those not employed outside the home spent more.

最終，他們的發現和此前對勞動者如何分配時間的研究所得出的結論大體相同。以前，美國女性曾在家中從事相當多的體力勞動。在1965年，她們花在清掃、做飯和洗衣服上的時間平均爲每週25.7個小時。無論藉助怎樣的工具，這些家務都會消耗相當多的能量。（研究者們沒有把照看孩子的時間計算在內，原因是這些女性在照看孩子方面的記錄存在矛盾而且經常和其他家務重疊在一起。）總的來說，當時職業女性在家務上花的時間較少，而家庭主婦在這方面所花的時間則較多。

Forty-five years later, in 2010, things had changed dramatically. By then, the time-use diaries showed, women were spending an average of 13.3 hours per week on housework.

45年後，也就是2010年，情況有了顯著變化。上述日記顯示，到2010年，美國女性花在家務上的時間平均爲每週13.3小時。

More striking, the diary entries showed, women at home were now spending far more hours sitting in front of a screen. In 1965, women typically had spent about eight hours a week sitting and watching television. (Home computers weren’t invented yet.)

更引人注目的是，在這些日記中，家庭主婦坐在電視或電腦前的時間大幅上升。1965年，美國女性每週看電視的時間通常爲八小時左右（當時還沒有出現家用電腦）。

By 2010, those hours had more than doubled, to 16.5 hours per week. In essence, women had exchanged time spent in active pursuits, like vacuuming, for time spent being sedentary.

到了2010年，這個數字提高了一倍以上，達到每週16.5小時。實際上，美國女性壓縮了用在清掃等動態行爲上的時間，而延長了靜坐不動的時間。

In the process, they had also greatly reduced the number of calories that they typically expended during their hours at home. According to the authors’ calculations, American women not employed outside the home were burning about 360 fewer calories every day in 2010 than they had in 1965, with working women burning about 132 fewer calories at home each day in 2010 than in 1965.

在這個過程中，她們在家裏消耗的熱量下降了很多。研究者們計算，2010年美國家庭主婦每天消耗的熱量比1965年減少了360大卡左右，對職業女性來說，這個數字約爲132大卡。

“Those are large reductions in energy expenditure, ” Dr. Archer said, and would result, over the years, in significant weight gain without reductions in caloric intake.

阿徹博士指出：“這在能量消耗方面是一個巨大退步。”如果不減少熱量攝入，長此以往體重就會明顯上升。

This does not mean, he said, that women — or men — should be doing more housework. For one thing, the effort involved is such activities today is less than it once was. Using modern, gliding vacuum cleaners is less taxing than struggling with the clunky, heavy machines once available, and thank goodness for that.

他說這並不意味着女性或男性應該分擔更多家務。首先，現在做家務已不像從前那樣耗費體力。謝天謝地，如今的吸塵器輕巧靈活，不像以前那樣笨拙沉重，使用起來也不再那麼費力。

Nor is more time spent helping around the house a guarantee of more activity, over all. A telling 2012 study of television viewing habits found that when men increased the number of hours they spent on housework, they also greatly increased the hours they spent sitting in front of the TV, presumably because it was there and beckoning.

其次，總的來說在家務上花更多時間並不能保證有更多的運動量。2012年一項關於看電視習慣的研究就生動地說明了這一點。這項研究表明，人們做家務的時間增多後，他們坐在那裏看電視的時間也會大幅上升，原因大概是開着的電視引起了他們的注意。

Instead, Dr. Archer said, we should start consciously tracking what we do when we are at home and try to reduce the amount of time spent sitting. “Walk to the mailbox, ” he said. Chop vegetables in the kitchen. Play ball with your, or a neighbor’s, dog. Chivvy your spouse into helping you fold sheets. “The data clearly shows, ” Dr. Archer said, that even at home, we need to be in motion.

阿徹博士說，相反，人們待在家裏時應該有意識地記錄自己的活動並設法縮短坐着的時間。他建議說：“走到信箱那兒取信”，到廚房切菜，和自己或者鄰居養的狗做遊戲，哄愛人幫你一起疊牀單。他指出，“這些數據清楚地表明”，就算在家，我們也需要動起來。