身高对青少年身体意象感知和行为的影响

中文摘要

本文估计了身高对青少年身体意象的因果效应，涵盖对体重的自我感知、这些感知的准确性以及体重管理意愿。利用1997年全国青年纵向调查（NLSY97）的数据，我们利用青少年时期身高的个体内变异，并以身体质量指数（BMI）为条件，以分离出身高对身体意象结果的影响。我们发现，即使在BMI保持不变的情况下，身高较高的青少年也更可能认为自己超重，且不太可能低估自己的体重类别。然而，误判方向因性别而异：身高较高的男孩更可能正确评估自己的体重类别，而身高较高的女孩则更可能高估自己的体重类别。这些感知变化转化为女孩的行为反应，但男孩则未见此转化。身高每增加一英寸，会使女孩报告希望减重的概率提高3.0个百分点（6.2%），且该效应集中在体重处于正常范围内的女孩中。综合来看，这些发现确立了身高是青春期身体意象的一个重要决定因素，其作用独立于体重。

Abstract

This paper estimates the causal effect of height on adolescents’ body image, encompassing self-perceptions of weight, the accuracy of those perceptions, and weight-management aspirations. Using data from the National Longitudinal Survey of Youth 1997 (NLSY97), we leverage within-individual variation in height during adolescence and condition on body mass index (BMI) to isolate the effects of height on body image outcomes. We find that taller adolescents are more likely to perceive themselves as overweight, even holding BMI constant, and are less likely to underestimate their weight category. However, the direction of misclassification diverges by gender: taller boys are more likely to correctly assess their weight category, while taller girls are more likely to overestimate it. These perception shifts translate into behavioral responses for girls but not for boys. A one-inch increase in height raises the probability that a girl reports wanting to lose weight by 3.0 percentage points (6.2 percent), with effects concentrated among girls in the normal weight range. Taken together, these findings establish height as a salient determinant of body image in adolescence, operating independently of body mass.