Living in a community where being overweight is common may incline individuals to becoming so themselves, a new study suggests

The US researchers wrote that a “clustering” effect has been observed with obesity, with some stakeholders suggesting that the pattern likely arises due to social contagion, due to social influences “such as social norms or mirroring”.

Others have disputed this claim, claiming that such clustering could be due to people’s tendency to associate with people like them, or that the clustering could be related to the influence of a shared environment, with similar access to green space and food options.

A new study, published in JAMA Pediatrics, looked at military personnel and their families who had been assigned to 38 military installations around the United States.

Members of 1519 families participated, including 1314 adults and 1111 children; and the sample was 40% white, 22% black, 24% Latin and 14% other races or ethnicities.

The researchers found that those personnel and families who moved to areas of higher obesity were more likely to also be obese, particularly if they had lived in the community for a longer period of time and lived off-base.

A one-percentage point higher county obesity rate was associated with a higher BMI (a difference of 0.08; 95%CI, 0.02-0.13) and greater odds of obesity (adjusted odds ratio [aOR], 1.05; 95%CI, 1.02-1.08) in parents, and a higher BMI z score (0.01; 95%CI, 0.003-0.02) and greater odds of overweight/obesity (aOR, 1.04; 95%CI, 1.01-1.06) in children.

The association between a higher-BMI community and higher BMI in participating individuals persisted even after controlling for shared built environments.

The inference was that obesity could be “socially contagious,” the authors wrote.

“Our results suggest that military families assigned to installations in counties with higher obesity rates were more likely to be overweight and/or obese than their counterparts assigned to installations in counties with lower obesity rates,” they wrote.

“The absence of evidence supporting self-selection or shared environment opens the possibility that social contagion may explain our findings.”

In a related editorial, stakeholders suggest that the idea that obesity can be contagious has public health policy implications, including the issue that parental obesity is a main risk factor for the development of obesity in childhood.

“It provides a stimulus to action to learn how to deactivate the ‘virus,’ preventing transmission

to future generations,” they write.