Recent research found a strong connection between teenagers’ weights and those of their friends. The data show that kids tend to interact in groups with others who have similar weight; so overweight children tend to spend time together.
The study, which will be in the journal Economics and Human Biology, looked at 5,000 teenagers, then followed up with many of them two years later, according to BBC News.
The weight changes overtime showed that a child’s weight gain could be associated with having a fat friend, which, according to the study, supported the theory of imitative obesity: mirroring the habits of one’s friends.
Using the Body Mass Index scale, a boy who is 5 feet 9 inches is technically healthy if he weighs around 147 pounds. If a friend who weighs the same and is at the same height later gains seven pounds, the boy is likely to gain two pounds, according to the study.
Even though that weight gain is not significant at first, if the gain continues overtime, the children could eventually become obese, if the pattern keeps going.
According to BBC News, the researchers said that the results do not show whether overweight kids simply stay friends throughout their teenage years, or if overweight teens influence their friends’ weight gains.
For Tam Fry, from the U.K.’s National Obesity Forum, the data may show a causative connection. Friends tend to share bad health habits, such as eating unhealthy items together.
"Other work has shown that you take on the weight attributes of your friends more than other people surrounding you...even if your friends live many miles away,” he said to the BBC. "If you go to dinner with your friends who are fat you are liable to eat the same foods that made them fat.”
On the other hand, kids are just as able to receive bad habits from their parents, with Fry stating that a parent who is overweight is less likely to engage in physical activity with their offspring
Fry concluded, "The answer is, in the end, to put in a lot of education and make sure children learn at an early age about the importance of leading an active life and eating healthily.” This way, he said, children could share good habits with friends who are overweight or obese.
Dr. Sally Kwak, one of the researchers from the University of Hawaii who worked on this study, seems to agree. She said that this evidence is important for U.S. lawmakers to consider as they work on targeted campaigns, according to the BBC—especially if one’s weight gain causes the friends to gain pounds as well.