Accuracy of Weight Perceptions in a Nationally Representative Cohort of US 8th Grade Adolescents

To describe the accuracy of weight perceptions in a nationally representative sample of US 8th graders, its relationship with weight control intentions (WCI), and the relationship of weight misperceptions and WCI with diet and activity behaviors.

Data analyzed came from the 8th grade wave (2006-2007) of the Early Childhood Longitudinal Study-Kindergarten Class, a nationally representative sample. Body mass index was calculated from height and weight measurements for 7800 8th graders (mean age 14.3 years). Measured weight status was categorized into underweight, normal weight, overweight, and obese using the US Centers for Disease Control and Prevention's age- and sex-specific growth charts. Self-reported weight status was compared with measured weight status to classify adolescents into accurate perceivers, overestimators, and underestimators. Multivariate logistic and negative binomial regression models were estimated for binary and count data outcome variables, respectively.

Overall, 42.1% of adolescents misperceived their weight status: 35.3% underestimated and 6.8% overestimated their weight status. Among overweight or obese adolescents, 68.4% misperceived their weight status; 35% of underweight adolescents overestimated their weight status. Among normal-weight adolescents, 8.5% overestimated and 18.5% underestimated their weight. Compared to accurate perception, both overestimation and underestimation of weight status were associated with greater likelihood of inappropriate WCI, but only underestimation was associated with unhealthy diet and activity behaviors.

Weight misperception was a common problem among US adolescents from all weight categories and was associated with inappropriate WCI. Future research should examine how adolescents' weight perceptions are formed and whether reducing misperceptions may improve behaviors.