Can obesity be contagious?

New research published in the New England Journal of Medicine says social networks can affect people's risk of obesity. Research results show that if you want to maintain a slim figure, it's best to keep your relatives and friends around you who are not obese.

The discovery stems from a study. As part of the Framingham Heart Study Project, the study surveyed 12067 individuals in a closely connected and complex network of social relationships between 1971 and 2003. All participants were tested for the Body Mass Index BMI, a measure of weight to body weight, and comprehensive statistical tests were also conducted to determine how weight gain among friends, compatriots, partners and neighbors affected their own weight.

The researchers marked the obviously obese people in the social network during this period, and found that the obese people expanded from a six-degree segmentation phenomenon, in which any two strangers in the world can establish contact through only six people, to a three-degree segmentation.

Over a certain period of time, if a person's friend becomes obese, the person's chance of becoming obese increases by 57%. If a sibling or spouse suffers from obesity, the person's chances of obesity increase by 40% and 37% respectively.

The study also pointed out that in general, if someone's social network is all same-sex, the risk of obesity is higher.

In contrast, environmental factors seem to have little impact on an individual's risk of obesity. For example, if people live in the neighborhood of obese people but are not in their social network, their chances of getting fat are not increased.

Another co-author of the study, Dr. James H. Fowler of the University of California, San Diego, said: "In fact, in my opinion, the social impact of obesity is much more important than people think. People have long struggled to identify the genes and physical processes that lead to obesity. However, our research shows that people should actually take the time to study obesity from a social perspective." (Internship Editor: Jiang Yan)