Supersize surprise
Ask anyone why there is an obesity epidemic and they will tell you that it’s al down to eating too much and burning too few calories. That explanation appeals to common sense and has dominated efforts to get to the root of the obesity epidemic and reverse it/ yet obesity researchers are increasingly dissatisfied with it. Many now believe that something else must have changed in our environment to precipitate(促成) 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 7 most plausible alternative explanations for the epidemic. Here they are.
1. 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-scale studies suggest there may be a link. People who sleep less than 7 hours a night tend to have a higher body mass index than people who sleep more, according to data gathered by the US National Health and Nutrition Examination Survey. Similarly, the US Nurses’ Health Study, which tracked 68,000 women for 16 years, found that those who slept an average of 5 hours a night gained more weight during the study period than 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 may precipitate weight gain.
Although getting figures is difficult, it appears that we really are sleeping less. In 1960 people in the US slept an average of 8.5 hours per night. A 2002 poll by the National Sleep Foundation suggests that the average has fallen to under 7 hours, and the decline 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’s going on in the world around us. We do this by altering our metabolic(新陈代新的) rate, shivering or sweating. Keeping warm 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 ambient temperatures(环境温度) have changed in the past few decades. Between 1970 and 2000, the average British home warmed from a chilly 13C to 18C. In the US, the changes have been at the other end of the thermometer as the proportion of homes with air conditionings rose from 23% to 47% between 1978 and 1997. In the southern states – where obesity rates tend to be highest – the number of houses with air conditioning has shot up to 71% from 37% 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. Studies show that in comfortable temperatures we use less energy.
3.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 isn 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 colleagres at the US National Center for Health Statistics in Hyattsville,Maryland, have calculated that people kicking the habit have been respousible for a small but significant portion of the US epidemic of fatness.From data collected aroud 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% of non-smokers and only 28%of smokers.
4. Genetic effects
相关问题推荐
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Section B
Directions:In this section, you are going to read a passage with ten statements attached to it. Each statement contains information given in one of the paragraphs. Identify the paragraph from which the information is derived. You may choose a paragraph more than once. Each paragraph is marked with a letter. Answer the questions by marking the corresponding letter on Answer Sheet 2.
Countries Rush for Upper Hand in Antarctica
A) On a glacier-filled island with fjords(峡湾)and elephant seals, Russia has built Antarctica’s first Orthodox church on a bill overlooking its research base. Less than an hour away by snowmobile. Chinese laborers have updated the Great Wall Station, a vital part of China’s plan to operate five basses on Antarctica, complete with an indoor badminton court and sleeping quarters for 150 people. Not to be outdone, India’s futuristic new Bharathi base, built on stills(桩子)using 134 interlocking shipping containers, resembles a spaceship. Turkey and Iran have announced plans to build bases, too.
B) More than a century has passed since explorers raced to plant their flags at the bottom of the world, and for decades to come this continent is supposed to be protected as a scientific preserve, shielded from intrusions like military activities and mining . But an array of countries are rushing to assert greater influence here, with an eye not just towards the day those protective treaties expire, but also for the strategic and commercial that already exist.
C) The newer players are stepping into what they view as a treasure house of resources. Some of the ventures focus on the Antarctic resources that are already up for grabs, like abundant sea life. South Korea, which operates state-of–the-art bases here, is increasing its fishing of krill(磷虾)，found in abundance in the Southern Ocean, while Russia recently frustrated efforts to create one of the world’s largest ocean sanctuaries here.
D) Some scientists are examining the potential for harvesting icebergs form. Antarctica, which is estimated to have the biggest reserves of fresh water on the planet. Nations are also pressing ahead with space research and satellite projects to expand their global navigation abilities.
E) Building on a Soviet-era foothold, Russia is expanding its monitoring stations for Glonass, its version of the Global Positioning System(GPS). At least three Russian stations are already operating in Antarctica, part of its effort to challenge the dominance of the American GPS, and new stations are planned for sites like the Russian base, in the shadow of the Orthodox Church of the Holy Trinity.
F) Elsewhere in Antarctica, Russian researchers boast of their recent discovery of a freshwater reserve the size of Lake Ontario after drilling through miles of solid ice. “You can see that we’re here to stay,” said Vladimir Cheberdak, 57, chief of the Bellingshausen Station, as he sipped tea under a portrait of Fabian Gottlieb von Bellingshausen, a high-ranking officer in the Imperial Russian Navy who explored the Antarctic coast in 1820.
G) Antarctica’s mineral, oil and gas wealth are a longer-term prize. The treaty banning mining here, shielding coveted(令人垂诞的)reserves of iron ore, coal and chromium, comes up for review in 2048. Researchers recently found kimberlite(金伯利岩) deposits hinting at the existence of diamonds. And while assessments vary widely, geologists estimate that Antarctica holds at least 36 billion barrels of oil and natural gas.
H) Beyond the Antarctic treaties, huge obstacles persist to tapping these resources, like drifting icebergs that could jeopardize offshore platforms. Then there is Antarctic’s remoteness, with some mineral deposits found in windswept locations on a continent that is larger the Europe and where winter temperatures hover around minus 55 degrees Celsius.
I) But advances in technology might make Antarctica a lot more accessible three decades from now. And even before then, scholars warn, the demand for resources in an energy-hungry world could ra
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She remains confident and ________ untroubled by our present problems.
A) indefinitely
B) infinitely
C) optimistically
D) seemingly
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The world's governments have done ________. nothing to combat the threat of nuclear accidents.
A．inherently
B．vitally
C．virtually
D．identically
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Passage Four Albert Einstein recalled his learning problems philosophically: “My intellectual (智力的) development was slow, as a result of which I began to wonder about space and time only when I had already grown up. Naturally, I could go deeper into the problem than a child.” And so, 11 years after dismissal from school, young Albert Einstein published the theory of relativity that changed our understanding of the universe.
No one in this century has been more widely recognized as a genius than Einstein. Yet his problems with early intellectual development and his peculiar gifts cast great doubt on all our conventional ideas about genius, intelligence or “I.Q.” (智商). On the one hand, Einstein showed early defects in abilities that our mental tests value; on the other hand, his special intellectual faculties went far beyond most definitions of intelligence. Moreover, their growth appears peculiarly gradual, contradicting the popular conception of intelligence as something inborn and fixed. His resolute persistence and his skills in playing games with ideas were apparently as decisive to his genius as any cutting edge of intellect (智能).
These powerful aspects of intelligence that conventional definitions overlook are getting close attention in a new wave of research. This comes after years of earlier studies which exposed the narrowness of our usual measures of mental ability. Intelligence, it turns out, is multifaceted and marvelous; it includes personal characteristics, creativity skills and intellectual capabilities that show up on no test. What is most exciting is that some of these iii-defined abilities are possessed by many people. Just knowing about such neglected skills will help us discover and develop untapped (未开发的) potential-in ourselves and in our children.
第15题：This passage is about ________.
A) the development of Einstein’s intellect
B) the wide recognition of Einstein as a genius
C) conventional ideas concerning genius
D) an insight to the complexity of human intelligence
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Questions 下列各are based on the following passage. Quite often, educators tell families of children who are learning English as a second language to speakonly English, and not their native language, at home. Although these educators may have good 36________,their advice to families is misguided, and it 37________from misunderstandings about the process of languageacquisition. Educators may fear that children hearing two languages will become 38________ confused and thustheir language development will be 39________; this concern is not documented in the literature. Children arecapable of learning more than one language, whether 40________or sequentially (依次地). In fact, most children outside of the United States are expected to become bilingual or even, in many cases,multilingual. Globally, knowing more than one language is viewed as an 41________ and even a necessity inmany areas. It is also of concern that the .misguided advice that students should speak only English is givenprimarily to poor families with limited educational opportunities, not to wealthier families who have manyeducational advantages. Since children from poor families often are 42________as at-risk for academic failure,teachers believe that advising families to speak English only is appropriate. Teachers consider learning twolanguages to be too 43________for children from poor families, believing that the children are alreadyburdened by their home situations. If families do not know English or have limited English skills themselves, how can they communicatein English? Advising non-English-speaking families to speak only English is 44________to telling them not tocommunicate with or interact with their children. Moreover, the 45________message is that the familys nativelanguage is not important or valued.
A．asset B．delayed C．deviates D．equivalent E．identified F．intentions G．object H．overwhelming I．permanently J．prevalent K．simultaneously L．stems M．successively N．underlying O．visualizing 第(36)题 __________