Part I writing (30 minutes)


Part II Reading Comprehension (Skimming and scanning) (15 minutes)

Supersize surprise

Ask anyone why there is an obesity epidemicand they will tell you that it’s al down to eating too much and burning too fewcalories. That explanation appeals to common sense and has dominated efforts toget to the root of the obesity epidemic and reverse it/ yet obesity researchersare increasingly dissatisfied with it. Many now believe that something elsemust have changed in our environment to precipitate(促成) such dramatic rises in obesityover the past 40 years or so. Nobody is saying that the “big two” – reducedphysical activity and increased availability of food – are not importantcontributors to the epidemic, but they cannot explain it all.

Earlier this year a review paper by 20obesity experts set out the 7 most plausible alternative explanations for theepidemic. Here they are.

1.      Not enough sleep

It is widely believed that sleep is for thebrain, not the body. Could a shortage of shut-eye also be helping to make usfat?

Several large-scale studies suggest theremay be a link. People who sleep less than 7 hours a night tend to have a higherbody mass index than people who sleep more, according to data gathered by theUS National Health and Nutrition Examination Survey. Similarly, the US Nurses’Health Study, which tracked 68,000 women for 16 years, found that those whoslept an average of 5 hours a night gained more weight during the study periodthan women who slept 6 hours, who in turn gained more than whose who slept 7.

It’s well known that obesity impairs sleep,so perhaps people get fat first and sleep less afterwards. But the nurses’study suggests that it can work in the other direction too: sleep loss mayprecipitate weight gain.

Although getting figures is difficult, itappears that we really are sleeping less. In 1960 people in the USslept an average of 8.5 hours per night. A 2002 poll by the National SleepFoundation suggests that the average has fallen to under 7 hours, and thedecline is mirrored by the increase in obesity.

2.      Climate control

We humans, like all warm-blooded animals,can keep our core body temperatures pretty much constant regardless of what’sgoing on in the world around us. We do this by altering our metabolic(新陈代新的) rate, shivering or sweating. Keepingwarm and staying cool take energy unless we are in the “thermo-neutral zone”,which is increasingly where we choose to live and work.

There is no denying that ambienttemperatures(环境温度) havechanged in the past few decades. Between 1970 and 2000, the average Britishhome warmed from a chilly 13C to 18C. In the US, the changes have been at theother end of the thermometer as the proportion of homes with air conditioningsrose from 23% to 47% between 1978 and 1997. In the southern states – whereobesity rates tend to be highest – the number of houses with air conditioninghas shot up to 71% from 37% in 1978.

Could air conditioning in summer and heating in winter really make adifference to our weight?

Sadlythere is some evidence that it does-at least with regard to heating.Studies show that in comfortable temperatures we use less energy.

3.Less smoking

  Badnews: smokers really do tend to be thinner than the rest of us,and quittingreally does pack on the pounds, though no one isn sure why. It probably hassomething to do with the fact that nicotine is an appetite suppressant andappears to up your metabolic rate.

Katherine Flegal and colleagres at the US National Center for HealthStatistics in Hyattsville,Maryland, have calculated that people kicking thehabit have been respousible for a small but significant portion of the USepidemic of fatness.From data collected aroud 1991 by the US National Healthand Nutrition Examination Survey,they worked out that people who had quit inthe previous decade were much more likely to be overweight than smokers andpeople who had never smoked .Among men, for example, nearly half of quitterswere overweight compared with 37% of non-smokers and only 28%of smokers.

4. Genetic effects

Yours chances of becoming fat may be set,at least in part,before youwere even born.children of boese mothers are much more likely to become obestthemselves later in life.Offspring of mice fed a high-fat diet during pregnancyare much more likely to become fat than the offspring of identical mice fed anormal diet. Intriguingly,the effect persists for two or threegenerations.Grand-children of mice fed a high-fat diet grow up fat even iftheir own mother is fed normally-so you fate may have been sealed even beforeyou were conceived.

5.A little older…

  Somegroups of people just happen to be fatter than others.surveys carried out bythe US national center for health statisties found that adults aged 40 to 79were around three times as likely to be obese as younger people.non-whitefemales also tend to fall at the fatter end of the spectreum:Mexican-americanwomen are 30% more likely than white women to be obsess,and black women havetwice the risk.

   Inthe US,these groups account for an increasing percentage of thepopulation.between 1970 and 2000 the US population aged 35 to 44 grew by43%.the proportion of Hispanic-americans also grew,from under 5% to 12.5% ofthe population,while the proportion of black Americans increased from 11% to12.3%.these changes may account in part for the increased prevalence ofobesity.

6.mature mums

   Mothersaround the world are getting older.in the UK,themean age for aving a frist child is 27.3,compared with 23.7 in 1970 .mean age at frist birth in the US hasalso increased, rising from 21.4 in 1970 to 24.9 in 2000.

   Thiswould be neither here nor there if it were’t for the observation that having anolder mother seems to be an independent risk factor for obesity. Results fromthe USnational heart,lung and blood institute’s study found that the odds of a childbeing obese increase 14% for every five extra years of their mother’s age ,though why this should be so is not entirely clear.

    MichaelSymonds at the university of Nottingham,UK,found that first-bron childrenhave more fat than younger ones. As family size decreases, firstbrons accountfor a greather share of the population. In 1964, british women gave birth to anaverage of 2.95 children;by 2005 that figure had fallen to 1.79. in the US in1976, 9.6% of woman in their 40s had only one chile;in 2004 it was 17.4%. thiscombination of older mothers and more single children could be contributing tothe obesity epidemic.

7.Like marrying like

Just as people pair off according to looks, so they do for size. Leanpeople are more likely to marry lean an d fat more likely to marry fat. On its own,like marrying like cannot account for any increase in obesity. But combinedwith others- particularly the fact that obesity is partly genetic, and thatheavier people have more children-it amplifies the increase form other causes.

1. A)effects of obesity on people’s health

  B)the link between lifestyle an obesity

   C)New explanations forthe obesity epidemic

  D)possible ways to combat the obesity epidemic

2. A)gained theleast weight

  B)were inclined to eat less

  C)found their vigor enhanced

  D)were less susceptible to illness

3. A)it makes us sleepy

   B)it causes sleep loss

  C)it increases our appetite

  D)it results from lack of sleep

4. A)it makes us stay indoors more

  B)it accelerates our metabolic rate

  C)it makes us feel more energetic

   D)it contributes to our weight gain

5. A)it threatens their health

  B)it heightens their spirits

   C)it suppresses their appetite

   D)itslows down their metabolism

6. A)heavy smokers

  B)passive smokers

  C)those who never smoke

   D)those who quit smoking

7. A)the growing number of smokers amongyoung people

   B)the rising proportion of minorities in its population

  C)the increasing consumption of high-calorie foods

  D)the improving living standards of the poor people

8.according to the US National Heart, Lungand Blood Institute, the reason why older mothers’ children tend to be obeseremains not entirely clear

9.According to Michael Symonds, one factorcontributing to the obesity epidemic is decrease of familysize

10 when two heavy people get married,chances of their children getting fat increase, because obesity is party genetiz

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