For overweight adolescents, experiencing discrimination or bullying in the first year of middle school may contribute to emotional issues seen in the third year by worsening loneliness and anxiety, a U.S. study suggests.
"We know that heavier youth are likely to be dissatisfied with their bodies at any one time," said lead author Jaana Juvonen of the University of California, Los Angeles.
"However, we were surprised at our longitudinal findings: that we can predict emotional problems during the last year in middle school (8th grade) based on youth's BMI during the first year (6th grade) in middle school when taking into account whether they have been mistreated by peers because of their weight," Juvonen told Reuters Health by email.
The researchers used data from a larger long-term study of 26 California middle schools, where data on body mass index (BMI), a measure of weight relative to height, was collected for about 5,000 kids in the spring semester of sixth grade - their first year in middle school - and again in seventh grade and eighth grade, the final year of middle school.
The kids, who were racially and ethnically mixed and about 52 percent female, also answered questions each year about their own emotional health, including body dissatisfaction, social anxiety and loneliness. They rated their experiences of bullying on questionnaires including items on exclusion, disrespectful treatment, threats or name calling by their peers because of their weight.
At each grade level, almost a quarter of kids were overweight or obese based on BMI categories, and one third of the entire group said they'd experienced at least one weight-based discrimination in seventh grade.
Researchers found that individual kids' perceptions of weight-based discrimination in seventh grade were a better predictor than actual BMI of their body dissatisfaction, social anxiety and loneliness in eighth grade, according to the report in Journal of Clinical Child and Adolescent Psychology.
For girls, this was also true for so-called somatic (physical) symptoms of emotional issues, such as headaches and nausea.
The results document an important process by which being overweight potentially leads to poorer mental health, said Joseph P. Allen of the University of Virginia in Charlottesville, who was not part of the new study. "Even after accounting for where they started, adolescents who experienced discrimination were more symptomatic two years later," he said by email.
"With non-experimental research, we can never prove causality," Juvonen said. "And we can obviously not randomly assign heavy youth to conditions where some get discriminated by their peers and others do not."
Still, "when no one wants to sit with Skyler, or Skyler never gets invited to parties or is publicly humiliated in front of others, it is easy to see why Skyler feels lonely or socially anxious," Juvonen said.
"Not only do we see peer discrimination predicting loneliness and social anxiety over time for both boys and girls, but we also see that girls who report such discrimination feel increasingly sick," she said. "Feeling physically sick, lonely, and socially anxious are likely to make youth withdraw from social situations."
Some body dissatisfaction can happen without peer discrimination, she noted. "Social comparisons to others (e.g., Facebook pictures, magazine photos) are likely to increase body dissatisfaction especially among girls because they compare themselves to (thin) ideals," Juvonen said. "If looks are important to them, they may also have low self-esteem or feel depressed."
Bullying shapes social norms by indicating what is not accepted or tolerated, and may extend even to kids in the healthy weight range, she said.
"Explicit efforts to address weight and body shape issues might be needed especially in middle school when bodies change at different rates and ways due to pubertal maturation," she said.
Adults should let students know just why making a "harmless" joke at someone else's expense reflects badly on the students using it, Allen told Reuters Health.