The Association between Weight Perception and BMI among High School Students

OBJECTIVE: To assess the association between weight perception and BMI among a large, diverse sample of adolescents. This study used both measured and self-reported height and weight to calculate BMI. RESEARCH METHODS AND PROCEDURES: A convenience sample of students (n = 2032) in grades 9 through 12 completed a questionnaire assessing demographic characteristics, self-reported height and weight, and body weight perception. These students were then weighed and had their height measured using a standard protocol. RESULTS: Using BMI calculated from measured height and weight, 1.5% of students were classified as underweight or at risk for underweight, 51.2% of students were normal weight, and 47.4% were overweight or at risk for overweight. Among this same sample of students, however, 34.8% perceived themselves as underweight, 42.9% perceived themselves as about the right weight, and 22.3% perceived themselves as overweight. Even when using BMI calculated from self-reported height and weight, >20% of students who were overweight or at risk for overweight perceived themselves as underweight. DISCUSSION: Because perception of overweight is a key determinant of adolescent nutritional habits and weight management, many students who are overweight or at risk for overweight but who do not perceive themselves as such are unlikely to engage in weight control practices. Increasing awareness of medical definitions of overweight might improve accuracy of weight perceptions and lead to healthier eating and increased physical activity.