Accuracy of self-reported weight compared to measured BMI among rural middle school students in Michigan

Aim Measured body mass index (BMI) is recommended for field-based assessments of overweight and obesity in all population groups. However, self-reported perception of body weight is frequently used in surveys targeting overweight and obese individuals. This study's purpose was to examine the accuracy of self-reported weight compared to measured BMI among rural middle school students in Michigan. Subject and methods A sample of 1995 students aged 11 and 12 were recruited over 5 years from six rural school districts in mid-Michigan. Data were collected using an interviewer-administered questionnaire with questions from the Youth Risk Behavior Survey. Height and weight were measured by research assistants and BMI calculated. Results Although only 3.5% of the students considered themselves very overweight, 26.4% were in the obese category of BMI. Almost a quarter (23.7%) reported they were slightly overweight, but these were all obese by BMI standards. Conversely, while 18.5% reported they were underweight, only 0.9% were truly underweight by BMI standards. A statistically significant difference (P < 0.001) was found in weight perception across BMI categories. Significant gender differences in perception were also found across all perceived weight categories. Conclusion It is imperative that children accurately perceive their body weight because this is the first step toward lasting behavior changes to achieve the optimal weight for their age and gender. However, when intervention programs use measured BMI rather than self-reports to define weight status among children and adolescents, it is more likely that overweight and obese children will be accurately targeted for intervention.