Study Says Obesity is Socially Contagious

Shared social behaviors like eating out and shared environments play a larger role in obesity than previously thought, according to a new study published in the Journal of Public Health. The findings suggest obesity is socially contagious and provides insight into to the transmission of obesity among friends and family.

Researchers from Arizona State University concluded shared ideas about acceptable weight or body size play only a minor role in spreading obesity among friends.

“When you see that something like obesity spreads among close friends and family members, this raises important questions about how it's spreading. Is it because we learn ideas about acceptable body size from our friends and family members, or that we hike together, watch TV together or go out to eat together?" they said. "If we can figure out exactly why obesity spreads among friends and family members, that can tell us where to focus resources in curbing rates of obesity. Is it more effective to change people's ideals of acceptable body size in hopes that they will change their behaviors or rather directly target socially shared behaviors that can contribute to weight gain or loss?"

To investigate how clustering of body attitudes account for the observed social contagion of obesity in past studies, the researchers interviewed 101 women from the Phoenix area and 812 of their closest friends and family members. Comparing the body mass index (BMI) of the women, their friends and family members, the researchers confirmed prior findings that the risk of a woman's obesity rose if her social network was obese. .

The team also examined three potential pathways by which shared ideals of acceptable body size might cause obesity and body size to spread through social ties. They found no evidence for the first and second pathways as means of transmission and only limited support for the third, suggesting other factors such as eating and exercising together may be more important in causing friends to gain and lose weight together.

The researchers said the strength of the study was the range of approaches taken to assess body size ideals, including ideal body size, anti-obesity preference and anti-fat stigma. For example, the participants were asked to choose whether they would rather be obese or have one of 12 socially stigmatized conditions, such as alcoholism or herpes. In many cases, the women would rather have more of the other conditions, with 25.4 percent preferring severe depression and 14.5 percent preferring total blindness over obesity.

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Arizona State University: Study gives clues to how obesity spreads socially