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  3. For most people, fat is a burden. It doesn’t really matter where it appears, we just don’t want it. But it turns out that our bo

For most people, fat is a burden. It doesn’t really matter where it appears, we just don’t want it. But it turns out that our bo

admin2012-05-28  99
问题     For most people, fat is a burden. It doesn’t really matter where it appears, we just don’t want it. But it turns out that our bodies also make a unique form of fat tissue that behaves remarkably unlike any other: rather than storing excess energy, this fat actually burns through it. It’s called brown fat and health experts confirm for the first time that healthy adults have stores of this tissue, which researchers hope to study further as a potential new weight-loss treatment.
    Human newborns have been known to have any significant deposits of brown fat, so called because of its abnormally high concentration of dark-colored mitochondria (线粒体), the engines that sustain cell activity. The primary purpose of brown fat is to regulate body temperature: the mitochondria-packed cells are designed to burn high quantities of sugar, and release that energy as heat—a mechanism that newborns rely on to keep themselves toasty.
    As people age, however, the body becomes better at regulating temperature, so brown-fat stores shrink and white fat starts to emerge. A research team in Sweden has found that healthy adults retain a sizable amount of fat in the front and back of the neck expressing the same proteins as brown fat.
    Identifying the presence of brown fat is one thing, but activating it to burn more sugar is another. Two studies confirmed that brown-fat cells become more active in the cold. But before we consider joining the Polar Bear Club, can brown fat actually cause weight loss? Brown fat may indeed allow a person to burn more calories with the same amount of consumption. On the basis of animal models, researchers calculate that 50g of brown fat could burn about 20% daily calorie an average person takes in. Leaner people tended to have more brown-fat deposits than overweight individuals. Interestingly, women were twice as likely as men to have active brown fat.
    Still, the findings don’t necessarily mean that activating brown fat leads to a slimmer waist. For one thing, the body is especially good at maintaining balance, which is why a boost in calorie-burning can often make a hunger signal and prompt people to eat more to make up for the loss. And even if drug companies could find a way to activate brown fat safely, that excess activity could throw off other metabolic (新陈代谢的) systems and damage your health.
Why does brown fat get smaller as people age?
选项 A、People are getting older and older.
B、We have a new kind of fat—white fat.
C、We don’t need it to regulate our temperature any more.
D、The humans only have it in the front and back of the neck.
答案C
解析 细节推断题。题干中的getsmaller是定位句中shrink的同义表达。定位句提到，随着年龄的增长，身体越来越善于调节体温。棕色脂肪含量也会下降。由此推断，C)“我们不再需要棕色脂肪来调节体温”符合文意。
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