首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Obesity Epidemic Ask anyone why there is an obesity epidemic and they will say that it’s all down to eating too much and burn
Obesity Epidemic Ask anyone why there is an obesity epidemic and they will say that it’s all down to eating too much and burn
admin
2009-08-19
23
问题
Obesity Epidemic
Ask anyone why there is an obesity epidemic and they will say that it’s all down to eating too much and burning too few calories. That is undoubtedly true. But it’s also true that we live in an "obesogenic (肥胖基因的) environment": calorific food is plentiful and cheap and our lifestyles are increasingly sedentary.
Now, obesity researchers are increasingly dissatisfied with such explanations. They believe that something else must have changed in our environment to cause such dramatic rises in obesity over the past 40 years or so. Nobody is saying that the "big two" -- reduced physical activity and increased availability of food -- are not important contributors to the epidemic. But they cannot explain it all.
Earlier this year a review paper by 20 obesity experts set out the 9 most plausible alternative explanations for the epidemic. Here they are.
Not Enough Sleep
It is widely believed that sleep is for the brain, not the body. Could a shortage of shut-eye also be helping to make us fat?
Several large epidemiological studies suggest there may be a link. People who sleep less than 7 hours a night tend to have a higher body mass index (BMI) than people who sleep more, according to data gathered by the US National Health and Nutrition Examination Survey. Similarly, the US Nurses Health Study found that those who slept an average of 5 hours a night gained more weight during the study period than those who slept 6 hours, who in turn gained more than those 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 may cause weight gain. One factor that could be at work here is the way sleep deprivation alters metabolism (新陈代谢). Leptin, the hormone that signals satiety (过饱), falls while ghrelin, which signals hunger, rises -- and this boosts appetite.
Climate Control
We humans, like all warm-blooded animals, can keep our core body temperatures pretty much constant regardless of what’s going on in the world around us. We do this by altering our metabolic rate, shivering or sweating. Keeping warm and staying cool take energy.
There’s no denying that surrounding temperatures have changed in the past few decades. In the US, the changes have been at the other end of the thermometer as the proportion of homes with air conditioning rose from 23 to 47 per cent between 1978 and 1997. In the southern states -- where obesity rates tend to be highest -- the number of houses with air con has shot up to 70 per cent from 37 per cent in 1978.
Could air conditioning in summer and heating in winter really make a difference to our weight? Sadly, there is some evidence that it does -- at least with regard to heating.
Less Smoking
Bad news: smokers really do tend to be thinner than the rest of us, and quitting really does pack on the pounds, though no one is sure why. It probably has something to do with the fact that nicotine is an appetite suppressant and appears to up your metabolic rate.
Katherine Flegal and colleagues at the US National Center for Health Statistics in Hyattsville, Maryland, have calculated that people kicking the habit have been responsible for a small but significant portion of the US epidemic of fatness. From data collected around 1991 by the US National Health and Nutrition Examination Survey, they worked out that people who had quit in the previous decade were-much more likely to be overweight than smokers and people who had never smoked. Among men, for example, nearly half of quitters were Overweight compared with 37 per cent of nonsmokers and only 28 per cent of smokers.
Prenatal Effects
Your chances of becoming fat may be set, at least in part, before you are even born. Children of obese mothers are much more likely to become obese themselves later in life. While this may be largely down to genetics, there is also evidence that some "intrauterine (子官内的) programming" goes on.
Offspring of mice fed a high-fat diet during pregnancy are much more likely to become fat than the offspring of identical mice fed a normal diet. And the effect persists for two or three generations. Grandchildren of mice fed a high-fat diet grow up fat even if their own mother is fed normally -- so your fate may have been sealed even before you were conceived.
Fat Equals Fecund
Heavier people have more children. A study by Lee Ellis at Minot State University in North Dakota found "small but highly-significant correlations" between BMI and reproductive rates. Women of normal weight or below had an average of 3.2 children, while overweight or obese women had an average of 3.5 children.
Does having more children make women gain weight, or does being overweight cause women to have more children? Probably both. Having lots of kids can increase the chances of getting fat -- if for no other reason than poor sleep. But Ellis also showed that people’s BMI before they become parents is associated with the number of children they eventually have.
As David Allison of the University of Alabama at Birmingham points out, obesity can. Lead to lower socioeconomic status, which in turn is associated with having more children.
So why is this relevant to the epidemic. It’s because obesity is heritable -- twin studies indicate it’s about 65 per cent genetic -- so a tendency for this to be associated with having a large family will cause the proportion 9f overweight people to go up.
A Little Older ...
Some groups of people just happen to be fatter than others. Surveys carried out by the US National Center for Health Statistics found that adults aged 40 to 79 were around three times as likely to be obese as younger people. Non-white females also tend to fall at the plumper end of the spectrum: Mexican-American women are 30 per cent more likely than white women to be obesity, and black women have twice the risk.
In the US, these groups account for an increasing percentage of the population. Between 1970 and 2000 the chunk of the US population aged 35 to 44 grew by 43 per cent. The proportion of Hispanic-Americans also grew, from under 5 per cent to 12.5 per cent of the population, while the proportion of black Americans increased from 11 to 12. 3 per cent. These demographic shifts may account in part for the increased prevalence of obesity.
More Drugs
In the 1970s a new class of antipsychotic (安定药) medication called neuroleptics came on the market, and millions of people worldwide now take these drugs. Alongside their undoubted success in treating psychosis, they have a drawback: users typically gain 4 kilograms in the first 10 weeks, and another 4 or 5 kg in the year that follows.
Neuroleptics are not the only class of drugs to cause weight gain: There are many drugs which have all been associated with packing on the pounds.
So have pharmaceuticals contributed to the obesity epidemic? There is no firm evidence either way, but there is no doubt that the use of all these drugs has mirrored the rise in obesity over the past 30 years.
Pollution
In daily life, people are exposed to tens of thousands of industrial chemicals: pesticides, dyes, perfumes, plastics, to name but a few. We swallow them, inhale them and absorb them through our skin.
There is some evidence that low levels of some of these chemicals can lead to weight gain. Mice given small amounts of the pesticide, for instance, more than doubled their body fat. Hexachloro-benzene, another pesticide, caused rats to gain significantly more than controls, despite eating half as much. Studies of humans exposed to PCBs by eating fish caught in North America’s Great Lakes have found similar associations: the more the toxic load, the greater the body weight.
Mature Mums
Mothers around the world are getting older. In the UK, the mean age for having a first child is 27.3, compared with 23.7 in 1970. Mean age at first birth in the US has also increased, rising from 21.4 in 1970 to 24. 9 in 2000.
Study found that the odds of a child being obese increases about 14 per cent for every five extra years of their mother’s age, though why this should be so is not entirely clear.
As family size decreases, firstborns account for a greater share of the population. In 1964, the British woman gave birth to an average of 2. 95 children; by 2005 that figure had fallen to 1.79. This combination of older mothers and more single children could be contributing to the obesity epidemic.
选项
答案
N
解析
本题涉及到肥胖流行的原因,从而将题目出处定位到文章前两段。这两段明确这四点的确引起肥胖,但文中没有把它们列成最重要的四点原因.所以题干中the first four具有迷感性,故答案为N。
转载请注明原文地址:https://kaotiyun.com/show/isdK777K
0
大学英语六级
相关试题推荐
说明:假如你是一家旅行社的经理李明。当地旅游职业学院外事办的王主任4月15日给你写信,询问是否能考虑赞助他们将在6月举办的为期一周的艺术节。你给王主任写封回信。时间:4月20日。内容:1.对他们的艺术节表示感兴趣并理解他们的需要;2.因为
A—OnseasonJ—OffseasonB—GuidepracticeK—LocaltouristorganizationC—TravelpressL—Board
A、OnThursdayevening.B、OnFridayevening.C、OnSunday.D、OnSaturday.C本题的问题关键词是when。对话中出现了三个日子,本题问男士观看表演的日子,所以是Sunday,选C。
______(do)wellinaninterviewwillbeanimportantpartofgettingaplaceatauniversity.
Thispartistotestyourabilitytodopracticalwriting.YouarerequiredtowriteaNoticeaccordingtothefollowinginformat
A、Onbusiness.B、Visitingclients.C、Signingacontract.D、Takingaholiday.A题目问的是格林先生在上海做什么?根据对话开头可知,男女双方在打电话。男士想找格林先生接听电话,女士告
Somepeoplearguethatself-plagiarism(自我剽窃)isimpossiblebydefinitionbecauseplagiarismistheftandpeoplecannotstealfro
A、Thereportedheroturnedtobehisfather.B、Hedidnotunderstandhisfathertilltoolate.C、Suchmisfortuneshouldhavefal
A、Sixisenough.B、Sixisnotenough.C、Themore,thebetter.D、Bringinallthechairs.CM:HowmanychairsshouldIbringinf
随机试题
农民画[河北2018]
不良
患者男性,60岁,心尖区听到舒张期隆隆样杂音,同时可听到收缩中晚期喀喇音,该患者可能是
“衣食住行”是人生最基本的需要。居住往往是其中实现的期间最长、所需资金数额最大的一项。根据规划目标的不同,居住规划主要分为3类,下列不属于这三类的是( )。
某市物资贸易公司总经理张某(系该市人大代表,住该市A区)与其公司职工李某(住该市B区)在该市C区的一家饭店吃饭。席间与该饭店服务员(住该市D区)发生争执。张某与李某将该服务员殴打造成重伤。公安机关将张某、李某实施刑事拘留,并报请检察院批准子以逮捕,侦查终
根据企业所得税法律制度的规定,企业缴纳的税金中,不得在计算企业应纳税所得额时扣除的是()。
人际交往必须以一定的___________为交往工具才有可能实现,___________和___________是主要的人际交往工具。
面对具有威胁性的突发事件,恐慌心理是人们进行自我保护的本能反应。但是,过度的恐慌反应,常常会导致比事件危害本身更为严重的消极后果。经验显示,在突发性公共事件中,许多损失可能不是事件本身造成的,而是由人们的过度恐慌导致的。这段文字意在强调(
Access中通配符“_”的含义是
说明:根据下列内容写一封邀请信。1.写信日期:2015年2月13日2.邀请人:张建国,东方集团公司人力资源部经理3.被邀请人:人事部门经理4.事由:召开人事管理研讨会5.主要内容:研讨新形势下人事管理的新模式和新方法6.主题报告人:滨海大学管
最新回复
(
0
)