Misperceptions of weight norms as a risk factor for overweight and underweight status among secondary school students

Overweight, obesity, and underweight are significant health concerns regarding adolescents in the United States. Erroneous perceptions of peer weight norms may be important risk factors for being underweight and overweight. Anonymous surveys were conducted to assess the accuracy of perceived peer weight norms among US youth in grades 6 through 12 from 2004 to 2008 across 8 states (n=28,738). Students reported their personal weight, height, and perceived peer weight by gender. Perceptions of the weight norm for same sex peers in one's grade in the local school cohort are compared to aggregate self-reports of weight for these same sex and grade cohorts in each school. Further, variation in perceptions is compared with personal BMI. Twenty-five percent of males and 21% of females overestimated peer weight norms by more than 5% (22 and 16 pounds on average, respectively). Underestimation occurred for 38% of males and 39% of females (16 and13 pounds on average, respectively). Overestimating peer weight norms was associated with significantly greater risk for being overweight or at risk for overweight for both males and females. Underestimating peer weight norms was significantly associated with a greater risk for being underweight or at risk for underweight for males and females. Multilevel regression analysis predicting BMI revealed perceived peer weight norm to be the strongest predictor compared to actual peer weight norms and demographic and environmental factors. Pervasive misperceptions of peer weight norms may contribute to unhealthy weight-related behaviors and help perpetuate the status of overweight or underweight students.