Overweight children have more unreciprocated friendships and frenemies than their thinner counterparts, a Keck School of Medicine of USC study finds.

In a survey of 504 preteens in the Netherlands, researchers found that overweight children are excluded from friendships, call classmates friends when the feeling is not mutual and are disliked by peers. And overweight children dislike more classmates than their thinner peers.

These heightened negative relationships take a mental, social and physical toll, said Kayla de la Haye, PhD, lead author of the new study and an assistant preventive medicine professor at the Keck School.

“Our finding is alarming because if we continue to have social environments where fat shaming is the norm, these kids will continue to be ostracized,” de la Haye said. “Those adverse interactions increase the risk of loneliness, depression, poor eating habits and illness.”

Although overweight children, on average, listed as many people in the friend category as children with healthy weight, they were 1.7 times more likely to be disliked and 1.2 times more likely to dislike their peers. These combined tendencies indicate that overweight children are generally involved in more unreciprocated friendships and mutual frenemy relationships, de la Haye said.

The study, published on June 7 in PLOS ONE, included 714 students, 210 of whom were nominated as friends but did not take the survey.

“Research by others has shown people who chronically feel isolated, lonely or socially disconnected experience greater inflammation and reduced viral suppression,” de la Haye added. “We’re not sure if that’s at play here, but a consistent body of research shows that negative social relationships can go under the skin and affect health.”

Worldwide, childhood obesity increased by 31 percent in a little over two decades with about 42 million overweight or obese children in 2013, according to the World Health Organization.

In the United States, the number of obese children has more than tripled since the 1970s. About 1 in 5 school-aged children are obese — about 17 percent of all children in America, according to the Centers for Disease Control and Prevention.

The prevalence of childhood obesity is higher among Latinos (22 percent) and blacks (20 percent) than among whites (15 percent), according to the CDC.

Isolation can create a vicious cycle for overweight children

The study is based on questionnaires that 504 preteens answered in the Netherlands when they were aged 10 to 12. Participants in 28 classes listed their best friends and their enemies. On average, 26 students participated per classroom.

Children were assigned weight categories based on their body mass index, a measure of body fat. About 16 percent of the participants were overweight.

Researchers controlled for gender because it can steer friendships and omitted children who had skipped a grade or who were held back a grade.

On average, children were listed as a friend by five of their classmates and as an enemy by two. However, overweight kids typically were considered a friend by just four classmates and were disliked by three.

“This social environment characterized by fewer friendships and more antipathies is likely to put overweight youth at increased risk for psychosocial maladjustment,” the study stated. “The resulting social isolation may also promote unhealthy behaviors, such as excessive food intake and decreased participation in sports and physical activities, which can lead to further weight gain and thus a cycle of poor physical and social outcomes.”

Unfortunately, it seems overweight children tend to have fewer friends and be friends with less popular kids who also tend to be overweight, de la Haye said.

“We want to reduce the stigma of being overweight,” she said. “We have anti-bullying campaigns based on sexual identity, race and ethnicity. We should do more to integrate obesity in our anti-bullying repertoire.”

The study used data from the Tracking Adolescents’ Individual Lives Survey, an ongoing research on the psychological, social and physical development of adolescents and young adults.

USC researchers are working across disciplines to improve children’s physical and mental health, boosting health across the life span. They have studied how “secondhand sugars” found in breast milk might negatively affect a baby’s future body weight, how a concussion might interrupt a child’s normal brain development and how teens in military families are at higher risk of depression and suicidal thoughts.

“Childhood obesity is a major focus area on both USC campuses,” said Keck School Dean Rohit Varma, MD, MPH, referring to the University Park and Health Sciences campuses. “USC-led research shows that children with asthma are more likely to become obese and little bribes spark better eating habits. Through continuous, multidisciplinary research across USC, we hope to bring about the decline of childhood obesity and its impact on children.”

— Zen Vuong