ESCH-SUR-ALZETTE, Luxembourg — More and more teens all over the world are underestimating their own body weight, according to a new research project that included over 745,000 adolescents from 41 countries. Study authors warn this trend could undermine, or render increasingly ineffective, ongoing public health interventions aimed at curbing childhood obesity rates.
Conversely, researchers from the University of Luxembourg utilized data spanning 2002 to 2018 to demonstrate a significant decline in those overestimating their weight too. The team behind these findings, a collection of international experts, warn that these observed shifts in body weight perception could reduce the effectiveness of public health interventions aimed at weight loss among young people.
“During this impressionable age, body weight perception may influence a young person’s lifestyle choices, such as the amount and types of food they eat and their exercise habits,” says lead author Doctor Anouk Geraets, from the Department of Social Sciences, at the University of Luxembourg, in a media release.
“So it’s concerning that we’re seeing a trend where fewer adolescents perceive themselves as being overweight – as this could undermine ongoing efforts to tackle increasing levels of obesity in this age group. Young people who underestimate their weight and therefore do not consider themselves to be overweight may not feel they need to lose excess weight and, as a result, they may make unhealthy lifestyle choices.”
How a person perceives their body weight doesn’t always necessarily reflect the reality of their weight. A discrepancy in body weight perception (BWP) either manifests as an underestimation (actual weight is higher than perceived weight) or an overestimation (actual weight is lower than perceived weight).
For this latest project, study authors analyzed survey data covering over 746,000 adolescents (ages 11-15) from 41 countries collected at four yearly intervals between 2002 and 2018 as part of the International Health Behavior in School-Aged Children (HBSC), a WHO collaborative study.
Researchers modeled trends in BWP among adolescents across different countries over extended periods of time, and were also sure to adjust for age, gender, and family socioeconomic status. Main findings include:
- Underestimation of weight status increased, while overestimation of weight status decreased over time among both sexes. Stronger trends were noted among girls, however.
- Correct weight perception increased over time among girls but decreased among boys.
- Changes in correct weight perception, underestimation, and overestimation of weight status differed across various countries. However, these changes were not explainable by an increase in country-level overweight/obesity prevalence.
Researchers speculate the observed differences between girls and boys in BWP may support the notion there are sex differences in body ideals – and that these body ideals have changed over time. More specifically, study authors say the increased underestimation and decreased overestimation of weight status over time among girls may be explained by the emergence of an athletic and strong body as a popular new contemporary body ideal for both sexes.
“This study has clinical and public health implications. The increase in correct weight perception and the decrease in overestimation may have a positive effect on unnecessary and unhealthy weight loss behaviors among adolescents, while the increase in underestimation might indicate the need for interventions to strengthen correct weight perception,” Dr. Geraets concludes.
“More research is now needed to understand the factors underlying these time trends and to develop effective public health interventions.”
While this particular research project was supported by a large number of participating countries, study authors admit the data only included nations in Europe, the United States, and Canada. Thus, these findings can’t be generalized to other regions. Additionally, while study authors were sure to adjust the models for certain potential confounding factors, several other factors (body image, dieting, changing eating patterns, migration) could have played a role in the observed trends over time.
The study is published in the journal Child and Adolescent Obesity.