Fewer teens consider themselves overweight and more underestimate what they weigh, a perception concerning to experts worried about childhood obesity.

These trends could reduce the effectiveness of public health interventions meant to help young people lose weight, researchers warn. Their findings were published July 3 in the journal Child and Adolescent Obesity.

“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,” lead author Anouk Geraets said in a journal news release. She is a postdoctoral researcher at the University of Luxembourg.

For the study, researchers reviewed 2002-2018 data involving more than 745,000 adolescents from 41 countries in Europe and North America. Information was collected at four-year intervals from kids who were 11, 13 and 15 years old.

Over the period, underestimation of weight status increased for both boys and girls, but the trend was stronger for girls.

Girls’ weight perception did get more accurate over time, however, but boys’ got worse.

These changes in correct weight perception varied across countries. They could not be explained by an increase in country-level overweight/obesity prevalence.

The authors noted that boys’ and girls’ body ideals may differ, which would explain why their perceptions differed. Body ideals have also changed over time, they pointed out.

The emergence of an athletic and strong body as a contemporary body ideal for both sexes may underlie some of these changes in weight perception, researchers said.

Geraets said the findings have 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,” she said.

More research is needed to understand underlying factors and develop public health interventions, Geraets added.

The results can’t be generalized to other regions of the world, researchers noted. Confounding factors, including body image, dieting, changing eating patterns and migration, may have also had an impact on these trends.

More information

The U.S. Centers for Disease Control and Prevention has more on childhood obesity.

SOURCE: Child and Adolescent Obesity, news release, July 3, 2023