Moving to a neighbourhood with a high obesity rate is likely to make a person become overweight, say researchers who suggest that your social circles can inadvertently influence your weight. "Social contagion in obesity means that if more people around you are obese, then that may increase your own chances of becoming obese," said Ashlesha Datar, a senior economist at University of Southern California in the US.
"In other words, living in a community where obesity is more common can make sedentary lifestyles, unhealthy eating and overweight or obesity more socially acceptable," said Datar, one of the authors of the study published in the journal JAMA Pediatrics.
Obesity is linked to many factors, including eating and exercise habits, genetics and the environment. Research shows that living in certain communities carries a higher risk of obesity than living in other communities, but this association has been challenging for scientists to explain.
Researchers studied military families to assess whether living in communities with greater obesity increased their own risk of being overweight or obese. Military families, they reasoned, cannot choose where they live -- rather, they are assigned to installations. Some of those installations are in counties with higher rates of obesity.
"We found that the families assigned to installations in counties with higher obesity rates were more likely to be overweight or obese than those assigned to installations in counties with lower rates of obesity," Datar said.
The researchers recruited families of US Army personnel at 38 military installations in the country to participate in surveys and measurements. In all, 1,314 parents and 1,111 children participated. Three-fourths of the parents and about one-fourth of the children were overweight or obese - reflective of the national rates.
Researchers found that the family's risk of obesity may increase or decrease, depending on the county obesity rate where they live. Moving to a county with a lower rate decreases the family's chances of becoming overweight or obese.
To assess whether shared environments could explain these results, the study accounted for extensive data on the food and activity opportunities in the county and neighbourhood, such as gyms and grocery stores.