The study was conducted by researchers at the Universite de Montreal, McGill University, Concordia University and the Ste. Justine Hospital Research Centre.
"When children's parents and schoolmates are overweight or obese, their own overweight status may seem normal by comparison. The higher the BMI of their friends and family, the more kids are likely to underestimate their weight - a trend consistent for both sexes, regardless of the socioeconomic levels of their school or family," said lead author Katerina Maximova, a PhD student in the Department of Epidemiology, Biostatistics, and Occupational Health at McGill University.
"Peers and parents have an enormous impact on kids' weight perception and when they live in environments in which people they see on a daily basis, such as parents and schoolmates, are overweight or obese, they may develop inaccurate perceptions of what constitutes appropriate weight status. So it is important that we help them correct their misperceptions and help them recognize that they may be at risk," Maximova added.
The study was part of the Quebec Health and Social Survey that investigated children from three different age groups - 9, 13 and 16 years old - from 178 schools across Quebec.
Researchers analyzed the body mass index (BMI) of 3,665 children and adolescents and found about 14 percent of students were overweight (BMI of 25 and over), 9 percent were obese (BMI of 30 and over), but only 1.6 percent of kids perceived themselves as having excess weight.
To analyze weight misperceptions, the researchers used the Stunkard Figure Rating Scale, which features images of seven sex-specific silhouettes that are underweight to obese.
Participants selected figures they perceived as corresponding to their appearance and researchers found that younger participants were most vulnerable to under-evaluating their weight.
"If you are surrounded by overweight people, you may be more vulnerable to distorted perceptions about your own weight," said Tracie Barnett, from the Université de Montréal Department of Social and Preventive Medicine and Ste-Justine Hospital Research Centre.
Compared to youth with healthy BMI's, overweight or obese kids were more likely to significantly underestimate their weight, which is the crux of the public health issue.
The study is published in a summer edition of the International Journal of Obesity.