If you really want to get slim, you may need to shed some of your heavier friends, scientists say.

科学家表示，如果你真想减肥，可能得避免跟胖朋友厮混了。

Researchers from Loyola University in Chicago found that students were more likely to gain weight if they had friends who were heavier than they were. However, they were more likely to either slim down, or at least gain weight at a slower pace, if their friends were leaner than they were.

芝加哥洛约拉大学的研究人员发现，如果朋友比自己胖，学生本人也很可能变胖。反之，如果朋友比自己瘦，那么本人则会变瘦，或者至少不那么容易变胖。

Dr David Shoham, who led the study, said their findings, published in the journal PLoS ONE, could help them develop better interventions¹ to treat obesity² in teenagers.

大卫-索哈姆博士组织了此次研究，研究成果发表在《PLoS ONE》杂志上。他认为这有助于他们更好地治疗青少年肥胖问题。

“We should not be treating adolescents in isolation,” he was quoted as saying by the Daily Mail. The study was designed to find out the reason why obesity and related behaviours appear to cluster in social networks.

“青少年肥胖问题不可孤立对待。”他对《每日邮报》说道。该研究旨在探究社会中肥胖及相关行为为何扎堆的问题。

The researchers wanted to know whether it is because friends influence one another’s behaviour or is it that teenagers befriend people who look similar to themselves.

研究人员想要查明，肥胖到底是受朋友影响，还是青少年喜欢跟气息相投的人扎堆的原因。

They examined data from two large high schools — one refered to as Jefferson High located in a rural area and has mostly white students and another mentioned as Sunshine High was an ethnically³ diverse urban school.

他们研究了两所大型高中的数据：一所是位于郊区的杰斐逊高中，以白人学生为主；另一所则是位于城市的阳光高中，各种族学生都有。

Students were surveyed during the 1994-95 school year and surveyed again the following school year. Researchers examined data from 624 students at Jefferson High and 1,151 students at Sunshine High. Their body mass index was calculated from their height and weight. A BMI over 25 is considered overweight and a BMI over 30 is considered obese⁴.

1994年到1995学年间，学生接受了一次调查，次年又被调查了一次。研究人员研究了杰斐逊高中624名学生以及阳光高中1151名学生的数据。学生的体重指数按照身高和体重计算。体重指数大于25为超重，大于30则为肥胖。

The researchers found that even after controlling for this friend-selecting process, there still was a significant link between obesity and a student’s circle of friends.

研究人员发现，即便对择友过程进行了控制，肥胖问题和学生所交的朋友仍然大有关系。

If a borderline overweight student at Jefferson School had lean friends there was a 40 percent chance the student’s BMI would drop in the future. However, if they had obese friends there was a 15 percent chance they would slim down.

在杰斐逊高中，肥胖学生如果有苗条的朋友，他的体重指数以后就有40%下降的几率。但是，如果他交了胖朋友，日后变瘦的几率就仅有15%。

The findings show that social influence “tends to operate more in detrimental⁵ directions, especially for BMI”, said the authors.

研究人员说，结果证明社会影响的“不利作用似乎很大，尤其在体重指数上。”

“Effective interventions will be necessary to overcome these barriers, requiring that social networks be considered rather than ignored,” Dr Shoham said.

“有效的干预将有助于克服上述问题，不过社会影响必须得到重视。” 索哈姆博士说道。

He noted⁶ that the study relied on self-reported data and was collected over a decade ago. Nevertheless, the results raised important questions about peer influence, he said.”Our results support the operation of both homophily and influence,” he added.

他还表示，此项研究的数据是十年前自动报告的数据，但研究结果还是引起了人们对同龄影响的疑惑。他说：“研究结果证明遗传和社会影响都能导致肥胖。”