Obesity is a socially contagious disease, previous disease has indicated.
However, findings from Arizona State University researchers have shed light on the transmission of obesity among friends and family.
According to the researchers, 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?" said Daniel J. Hruschka, lead author with ASU's School of Human Evolution and Social Change.
Researchers interviewed 101 women from the Phoenix area and 812 of their closest friends and family members to establish how clustering of body attitudes account for the observed social contagion of obesity in past studies.
By comparing the body mass index (BMI) of women participants, 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 study also suggests that other factors such as eating and exercising together may be more important in causing friends to gain and lose weight together.
"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 Brewis, director of the Center for Global Health in ASU's College of Liberal Arts and Science.
The research has been recently published online in the American Journal of Public Health.