The development of associations among body mass index, body dissatisfaction, and weight and shape concern in adolescent boys and girls

Purpose: To examine how the associations among body mass index (BMI) and body dissatisfaction and weight and shape concern evolve from late childhood through late adolescence in boys and girls.

Methods: We analyze data from subjects aged 9-18 years from the Growing Up Today Study, a national prospective cohort of U.S. youth (n = 16,882, yielding 59,750 repeated-measures observations during five waves of data collection). Generalized additive models produced curves of association for body dissatisfaction and weight concern across BMI percentiles. Generalized estimating equations (adjusting for correlated within-subject repeated measures, sibling clusters, pubertal maturation, and region of residence) tested main and interactive effects of BMI, age, and gender.

Results: Girls above the 50th BMI percentile reported greater body dissatisfaction than girls below the 50th percentile. By contrast, boys who reported the most body dissatisfaction were either above the 75th BMI percentile (approaching overweight) or below the 10th percentile (approaching underweight). Body dissatisfaction increased with age for both girls and boys, but the gender-specific patterns of BMI effects remained constant. Male and female participants in the overweight/obese BMI range reported the greatest weight concern, but among older adolescents (particularly girls), healthy weight became increasingly associated with greater weight and shape concern.

Conclusions: Body dissatisfaction and weight and shape concern intensify across adolescence, but associations between the constructs and BMI remain gender specific. Findings have important implications for eating disorder risk assessment and prevention.