Diagnosing underweight in adolescent girls: Should we rely on self-reported height and weight?

This study examines the reliability of self-reported height, weight and weight change in underweight versus normal weight adolescent females. Self-reported height and weight were obtained from 162 schoolgirls without an eating disorder (12–16 years), and compared to objective measurements afterwards. Weight change was assessed 4 months later. The influence of age and current BMI on the reliability of self-reports was analyzed by linear regression analyses. With increasing age, height and BMI were reported more accurately. With increasing BMI, the underestimation of weight increased. Underweight girls overestimated their weight significantly compared to normal weight girls. Only 41% of the girls with a weight loss (> 1 kg) in the past 4 months reported this accurately. Therefore, especially in younger girls with low body weight, information on height and weight as well as weight changes should be obtained objectively to identify a developing or subthreshold anorexia nervosa.

► The reliability of height and weight self-reports of adolescent girls was examined.
► With increasing age, height and BMI were reported more accurately.
► With increasing BMI, the underestimation of weight increased.
► Underweight girls overestimated their weight compared to normal weight girls.
► Only 41% of the girls with weight loss in the past 4 months reported this properly.