The Science Behind the Numbers That Govern Our Lives A)Numbers are everywhere in your life. You can assign a number to just abou

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问题                 The Science Behind the Numbers That Govern Our Lives
A)Numbers are everywhere in your life. You can assign a number to just about anything. Numbers work because they get our attention, but they’re also fairly easy to manipulate. Here’s the latest thinking about the science behind the numbers that govern our lives.
5 portions of fruit and vegetables a day
B)"It’s a lot more useful than ’eat a varied diet’," says Mike Rayner, director of the Nuffield Department of Population Health, "because how do we know what that really means? Health messages tend to work if they capture the public’s imagination. There’s a mixture of art and science in setting them at the right level, between what’s ideal and what’s pragmatic. "
C)And so it was with the five-a-day campaign, which began in 1994. "We adopted a five-a-day message because the Americans had a similar scheme, and the World Health Organisation’s recommendation was 400g a day, which was about 50% more than the average person in the UK was eating," Rayner says. But in the countries where the WHO had found the lowest levels of heart disease and cancers linked to diet, the average person was eating far more fruit and vegetable—around 10 portions a day—and other countries recommend greater amounts: in Denmark, it’s 600g; in Greece, it’s six portions of vegetables and three of fruit. So although five will do you good, more might be better. It’s estimated that most people in the UK still average only three portions. "Based on this rate of increase," Rayner says, "it will take decades before we’re hitting the target."
2 000 calories a day for women, 2 500 for men
D)In the documentary Super Size Me, Morgan Spurlock’s camera crew ask people on the street to define "calorie". Most can’t. As Marion Nestle and Maiden Nesheim recount in their book Why Calories Count: From Science To Politics, Spurlock’s crew "could not find even one person who could come up with a reasonable definition".
E)There are actually five different measurements for calories as a unit of energy. The guideline we most commonly think of—2 000, or 2 500 a day—is in calories with a small c. Around two-thirds of the total calories you need are defined by your basal metabolic rate(BMR)—the amount of energy you expend just existing: that’s breathing, brain function, blood circulation. On top of that, anything you do, including shivering or fidgeting(坐立不安), let alone walking or running, will increase the number of calories you need.
F)Your BMR is affected by your weight and height(different formula will give different totals)and the amount of activity each of us does each day will vary greatly. So do the average calorie guidelines really apply to any of us? "It’s hard to arrive at anything approaching the correct number without doing expensive tests involving non-radioactive isotopes(同位素)," admits Nestle. So, would we be better off using one of those online calculators that gives us an individual number? "Good grief, no," she says. "If you are going to buy anything, get a scale that works. And use it. By adulthood, people know whether or not they have a weight-gain problem. If they do, they need to eat less. This isn’t rocket science. It’s just figuring out how to balance food intake against calorie needs, and a scale tells you everything you need to know. "
G)So why do we bother having recommended averages at all? Because, Nestle says, most of us dramatically underestimate how many calories there are in food and, therefore, what a portion size should look like. "If I had one thing to teach the world, it would be that larger portions have more calories," she says. "I wish this were as intuitive as it sounds, but it’s not. "
8 hours’ sleep a night
H)For every person who will tell you that Margaret Thatcher got by on four hours a night, a study will show that the average person needs between seven and nine hours of sleep to function well. If you regularly average less than seven hours, then you have an increased risk of depression, diabetes and heart problems. But sleeping for more than nine hours a night has also been associated with an increase in the likelihood of physical and mental-health issues.
I)Myths about our sleep abound. Is every hour of sleep before midnight worth more than the hours after? There’s little evidence to support this, although one study showed that people performed better when they’d had more sleep after midnight, contradicting the myth. Do you need to get your sleep in one block? Again, this may not be true. But some historians believe that "segmented sleep" used to be the norm. Roger Ekirch made a study of sleep throughout the ages, and found many references in different languages to a "first" and "second" sleep. People would get up between the sleeps, and use the time to pray, reflect on their dreams, have sex or even visit neighbors.
J)Dr. Thomas of the US Institute of Mental Health asked patients to spend a month living without artificial light. By the end of his experiment, the patients had all fallen into a pattern of sleeping for three or four hours, waking for an hour or so then sleeping for another four hours or so, and they reported never having felt so rested. What is almost certainly important, though, is going through the different stages of the sleep cycle, from light, to "slow wave", to REM(the average person goes through about four or five sleep cycles of 90-120 minutes a night). If your sleep is constantly interrupted, your body may not be reaching the right state of sleep it needs in order to repair itself.
30 minutes’ exercise, 5 times a week
K)Despite our 2012 Olympic summer, a report from Sport England found that the number of adults playing traditionally popular sports such as football, rugby and squash has fallen in the past year.
L)You’ve probably heard that the recommended amount of exercise is half an hour’s moderate aerobic(有氧的)activity at least five times a week. The official guideline from the Department of Health is at least 150 minutes a week, so it suggests you break it up into five half-hour sessions. But, within that, there are other suggestions. On two days or more a week, your physical activity should include strengthening exercises that work all the major muscle groups. Oh, and instead of 150 minutes of moderate exercise, you could do 75 minutes of vigorous intensity activity, "such as running or a game of singles tennis"(plus your muscle strengthening). Or, if you like, you can do a mix of the two. Not exactly catchy, is it?
M)"Sometimes messages are refined for the sake of making them more accurate, but it means people can’t always remember what they are," Nuffield’s Mike Rayner says. "These things only need to be changed lightly and only when they are overwhelmingly out of date. "
N)Even if you’re meeting the recommended quota, it will only count for so much if you then drive to work and sit at a computer for nine hours. A review by the American Journal of Clinical Nutrition conceded that the average of 30 minutes daily "may be insufficient to prevent unhealthful weight gain for some, perhaps many, but probably not all, persons".
The scheme of half an hour’s exercise at least 5 times a week requires that you’d better exercise your major muscle groups at least twice or more during that period.

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答案L

解析 细节推断题。L)段前两句介绍了“每周最好保持五次每次半小时的适度有氧运动”这条建议,第三、四句提到,在这条建议内,又有一些其他建议,每周至少两天,你的身体运动应包含能够锻炼到身体各大肌肉群的强化训练。题干是对定位句的概括,故答案为L)。
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