A three-year study found severely obese adolescents are no more likely to be depressed than normal weight peers.
However, it found that white adolescents might be somewhat more vulnerable to psychological effects of obesity.
The study - conducted by researchers from the Center for Child and Adolescent Health Policy at Mass General Hospital for Children (MGHfC) and the Department of Public Health and Community Medicine at Tufts Medical School - analyzed the relationship between severe obesity and depressive symptoms in a community-based sample of non-Hispanic black and white adolescents.
"People assume that all obese adolescents are unhappy and depressed; that the more obese a teen may be, the greater the impact on his or her mental health. Our findings suggest this assumption is false," said Elizabeth Goodman, director of MGHfC and lead author of the study.
The study included 51 severely obese participants (body mass index greater than or equal to 40 and higher than 95 percent of their age group), between grades 7-12 and an equal number of non-obese participants matched for age, gender and race.
Depressive symptoms were analyzed using a standard assessment tool at the study outset and reassessed two and three years later.
The study found no relationship between participants' weight status and the likelihood of being depressed.
An association between obesity and higher depressive symptoms was seen, but only in white participants and only at the three-year assessment, not at baseline or at two years.
The study has been published online in the Journal of Adolescent Health.