The number of teenagers who underestimate their body weight has increased significantly, potentially undermining public health campaigns targeting obesity, a team of international researchers have said.
In a new study, which analysed weight perceptions of more than 745,000 adolescents across 41 different countries, including the UK and the USA, teenagers were more likely to underestimate their own weight today than twenty years ago.
The findings, which are published in Child and Adolescent Obesity, also show a noticeable reduction in young people overestimating their weight.
Researchers warn that the shifting perceptions of body weight could reduce the effectiveness of public health interventions.
Body weight perception (BWP) is associated with health behaviours, and underestimating or overestimating weight can lead to poor health choices.
In this study, the researchers examined how BWP has changed with time. The data from 746,121 children aged 11, 13 and 15 was collected between 2002 and 2018 at four-year intervals. This was part of the International Health Behavior in School-Aged Children (HBSC), a collaborative study involving the World Health Organisation (WHO).
The results show that the underestimation of weight status has increased over time, with more young people perceiving themselves as a lower weight than they are. Equally, the overestimations of weight status has decreased over time, with fewer young people thinking their weight is higher than it is. These trends were found to be true across both genders but were seen more strongly in girls.
Dr Anouk Geraets, lead author of the study from the University of Luxembourg, said: ‘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 overweight may not feel they need to lose excess weight and, as a result, may make unhealthy lifestyle choices.’
The changes in correct weight perception, underestimation and overestimation of weight status, differed across different countries but did not correlate with a country’s obesity levels. Accurate weight perception increased over time for girls, and in contrast, it decreased among boys. The researchers believe this may be due to sex differences in body ideals which may have changed over time, most noticeably with the more recent emergence in popularity of a strong athletic body for both boys and girls.
Dr Geraets added: ‘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 behaviours among adolescents, while the increase in underestimation might indicate the need for interventions to strengthen correct weight perception.’
The researchers stated that more research is needed to understand more clearly the factors underlying these time trends and develop appropriate public health interventions.