Scientists Say Getting Fat Can Spread Like the Flu

Put down the pizza, and take a look around. How could your environment be influencing your weight gain? This is the question two economists set out to answer in a recent study. Researchers have previously discovered that mood might be contagious. So what has this new study discovered about weight and social contagion?

Researchers looked into how weight gain can spread

Teenage Girl Fastening Pink Trousers

Where you live makes a difference in weight gain. | iStock.com/monkeybusinessimages

The JAMA Pediatrics study set out to determine whether living in communities with higher populations of overweight or obese residents would have an influence on an individual’s weight through social contagion. Ashlesha Datar, a University of Southern California senior economist, and Nancy Nicosia, a Rand Corporation senior economist, pulled data from studies of military families across the United States.

The children and parents surveyed were stationed on one of 38 different military bases nationwide. By using military families, the researchers found a control group that wasn’t separated according to weight. And they analyzed how their locations might have affected each of their individual weight gains.

Next: The research they based their study on

They based their research on how smoking and happiness spread

Man smoking a cigarette

Smoking is another behavior that spreads. | iStock.com/Minerva Studio

They based their theory on a study of smoking. That found smoking behavior is more likely to spread among friends and family. Plus, the people you surround yourself with often alter emotions. And even divorce is a potential social contagion.

Next: If this one thing is prevalent in your life, it could affect your weight gain.

Social media is a big influence

Woman looking on social media applications

Yes, social media can have an impact on weight gain. | iStock.com/Anatolii Babii

The smoking study confirmed what we’ve long known: Social networking regularly influences us in many ways, including physical weight gain. The researchers, who noticed the prevalence of peer influence on individual obesity, found others’ portrayal of their happiness and eating habits left an impression on their social media followers.

Harvard Health Letter’s Anthony Komaroff, M.D., analyzed the study. “If people see their friends becoming heavier and heavier over time, they may accept weight gain as natural, even inevitable,” he wrote. “Instead of exercising more or eating less when their weight begins to creep up, they may simply go with the flow and join the crowd.”

Next: The researchers discovered a startling fact.

Where you live could affect your weight gain

Bossier City, LA, USA

Where you live makes a difference. | iStock.com/SeanPavonePhoto

The JAMA study revealed where each military family was stationed did indeed play a role in their weight gain. The parents and children stationed on bases where the county had a higher obesity rate were more inclined to gain weight or become obese while living there — and vice versa.

For every percentage point that a specific county’s obesity rate rose, the researchers noticed the likelihood a child would be overweight or obese rose 4% to 6% and their parents’ chance rose 5%. Those who lived off-base were more likely to gain weight than those who were on-base. That was likely due to influence from the community they were adapting to.

Next: Have you moved recently?

How long you live there might play a role, as well

People walking on the city street.

The time you spend in a city also makes a difference. | Dovapi/iStock/Getty Images

Teenagers who lived on or near the base for years were more likely to be influenced by their county’s obesity rate than those who had just moved to a new county. This suggested the more exposure a family had to the county’s obesity level, the more likely they were to adopt their neighbors’ “weight status.”

Next: Your parents’ influence on your weight gain differs from that of your friends.

Certain relationships have a greater effect

Friends hands toasting red wine glass and having fun outdoors cheering with winetasting - Young people enjoying harvest time together at farmhouse vineyard countryside - Youth and friendship concept

How much your friends eat and drink will impact your waistline. | ViewApart/iStock/Getty Images

The study found spending time with certain people can correlate to weight gain, as well. However, it concluded that the relationship to the person is crucial in determining how their weight gain might influence you.

Study participants with obese friends had a 57% higher chance of becoming obese. And those with an obese sibling had a 40% higher chance. A New England Journal of Medicine study identified obesity as a social contagion, as well. It reported that if an individual’s friend, sibling, or spouse became obese over a certain period of time, the individual’s chances of becoming obese increased by 37% to 57%.

Next: Let’s summarize the study.

In conclusion …

Teenage Girl Sitting On Floor

Keep an eye on the scale. | Highwaystarz-Photography/iStock/Getty Images

“Social contagion may explain our findings,” the study’s authors said. Leonard H. Epstein, Ph.D., and Xiaozhong Wen, M.D., Ph.D., of the University of Buffalo’s Division of Behavioral Medicine, wrote an editorial to accompany the findings. “The idea that obesity is contagious and can spread like a virus was a brilliant analogy,” they said, for how you can adopt the habits of those you spend time with.

“If social contagion is having an effect, you would expect the longer the exposure, the greater the risk, which is what [Datar and Nicosia] found,” Epstein and Wen wrote.

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