Obesity can spread from person to
person, much like a virus, researchers are reporting today. When one person
gains weight, close friends tend to gain weight, too. Their
study, published in The New England Journal of Medicine, involved a detailed
analysis of a large social network of 12,067 people who were been closely
followed for 32 years, from 1971 to 2003. The investigators
knew who were friends with whom as well as who was a spouse or sibling or
neighbor, and they knew how much each person weighed at various times over three
decades. That let them reconstruct what happened over the years as individuals
became obese. Did their friends also become obese? Did family members? Or
neighbors? The answer, the researchers report, was that people
were most likely to become obese when a friend became obese. That increased a
person's chances of becoming obese by 57 percent. There was no effect when a
neighbor gained or lost weight, however, and family members had less influence
than friends. It did not even matter if the friend was hundreds
of miles away, the influence remained. And the greatest influence of all was
between close mutual friends. There, if one became obese, the other had a 171
percent increased chance of becoming obese, too. The same
effect seemed to occur for weight loss, the investigators say. But since most
people were gaining, not losing, over the 32 years, the result was, on average,
that people grew fatter. Dr. Nicholas A. Christakis, a
physician and professor of medical sociology at Harvard Medical School and a
principal investigator in the new study, said one explanation was that friends
affected each others' perception of fatness. When a close friend becomes obese,
obesity may not look so bad. "You change your idea of what is
an acceptable body type by looking at the people around you," Dr. Christakis
said. The investigators say their findings can help explain why
Americans have become fatter in recent years—each person who became obese was
likely to drag along some friends. Their analysis was unique,
Dr. Christakis said, because it moved beyond a simple analysis of one person and
his or her social contacts and instead examined an entire social network at
once, looking at how a person's friend's friends, or a spouse's sibling's
friends, could have an influence on a person's weight. The
effects, he said, "highlight the importance of a spreading process, a kind of
social contagion, that spreads through the network." Of course, the
investigators say, social networks are not the only factors that affect body
weight. There is a strong genetic component at work, too.
Science has shown that individuals have genetically determined ranges of
weights, spanning perhaps 30 or so pounds for each person. But that leaves a
large role for the environment in determining whether a person's weight is near
the top of his or her range or near the bottom. As people have gotten fatter, it
appears that many are edging toward the top of their ranges. The question has
been why. If the new research is correct, it may say that
something in the environment seeded what some call an obesity epidemic, making a
few people gain weight. Then social networks let the obesity spread
rapidly.
单选题
Who had the greatest influence on people who became obese?
单选题
According to Dr. Nicholas A. Christakis, what is the explanation for
friends being the greatest influence?
A. Friends usually spend a lot of time together.
B. Friends share similar eating habits.
C. Friends are more important than family members.
D. Friends affected each others' feelings of fatness.
【正确答案】
D
【答案解析】[解析] 细节题。根据Dr. Nicholas A. Christakis回到原文定位到第七段和第八段，陈述了Dr. Nicholas A. Christakis对于这种现象的解释：朋友之间对于肥胖的感知是互相影响的。一个人的亲密好友很胖，那么他对于什么是可接受体型的态度也会发生改变，肥胖在他看来也不会很令人不快。
单选题
Which factor of becoming obese is not mentioned in this report?