Obesity has been confirmed to be socially contagious by research recently published online in the American Journal of Public Health.
Research from Arizona State University sheds light on how it is "caught" between friends and families. According to the study, shared ideas about acceptable weight played only a minor role in spreading obesity among social circles.
The article "Shared Norms and Their Explanations for the Social Clustering of Obesity" suggests that it's what people do with each other that explains why people lose and gain weight with their friends, rather than how they think like one another.
The ASU team interviewed 101 women from the Phoenix area and 812 of their closest friends and family members.
When comparing the body mass index of a woman and her friends and family, researchers confirmed that a woman's risk of obesity rose if her social network was obese.
They then explored the reason this may occur. They came up with three hypotheses:
"You might learn what is an acceptable body size from your friends and then change your diet and exercise to try to achieve that," researchers explained in a press release. "Or, you might not agree with what your friends or family members think, but still feel pressure from them to achieve some ideal body size. Finally, you may form an idea of appropriate body size by simply observing your friends' bodies, which in turn changes your eating and exercise habits."
The team found that women did not become obese based on the first two hypotheses. The third, however, was proven to be an influential reason since eating and exercising together led to friends gaining and losing weight together.
The study also measured how women view obesity. Participants were asked to choose whether they would rather be obese or have one of 12 socially stigmatized conditions, such as alcoholism or herpes. 25.4 percent preferred severe depression and 14.5 percent preferred to be totally blind.
"This study is important because it shows that while the clustering of people with larger or smaller bodies is real, it is not shared values between friends that accounts for it," said Alex Brewis, a biological anthropologist at Arizona State University. "This gives us important clues about the best ways to tackle obesity as a public health issue; we need to focus on what people do together, rather than what people think."