Telford R D, Cunningham R B, Abhayaratna W P
UC National Institute of Sports Studies, University of Canberra, Canberra, ACT, Australia; Clinical Trials Unit, Academic Unit of Internal Medicine, Canberra Hospital, Garran, ACT, Australia.
Pediatr Obes. 2014 Dec;9(6):448-54. doi: 10.1111/j.2047-6310.2013.00194.x. Epub 2013 Aug 14.
The index of body mass related to stature, (body mass index, BMI, kgm(-2) ), is widely used as a proxy for percent body fat (%BF) in cross-sectional and longitudinal investigations. BMI does not distinguish between lean and fat mass and in children, the cross-sectional relationship between %BF and BMI changes with age and sex.
While BMI increases linearly with age from age 8 to 12 years in both boys and girls, %BF plateaus off between 10 and 12 years. Repeated measures in children show a systematic decrease in %BF for any given BMI from age 8 to 10 to 12 years. Because changes in BMI misrepresent changes in %BF, its use as a proxy of %BF should be avoided in longitudinal studies in this age group.
Body mass index (BMI, kgm(-2) ) is commonly used as an indicator of pediatric adiposity, but with its inability to distinguish changes in lean and fat mass, its use in longitudinal studies of children requires careful consideration.
To investigate the suitability of BMI as a surrogate of percent body fat (%BF) in pediatric longitudinal investigations.
In this longitudinal study, healthy Australian children (256 girls and 278 boys) were measured at ages 8.0 (standard deviation 0.3), 10.0 and 12.0 years for height, weight and percent body fat (%BF) by dual-energy X-ray absorptiometry.
The patterns of change in the means of %BF and BMI were different (P < 0.001). While mean BMI increased linearly from 8 to 12 years of age, %BF did not change between 10 and 12 years. Relationships between %BF and BMI in boys and girls were curvilinear and varied with age (P < 0.001) and gender (P < 0.001); any given BMI corresponding with a lower %BF as a child became older.
Considering the divergence of temporal patterns of %BF and BMI between 10 and 12 years of age, employment of BMI as a proxy for %BF in absolute or age and sex standardized forms in pediatric longitudinal investigations is problematical.
在横断面和纵向研究中，与身高相关的体重指数（体重指数，BMI，kg/m²）被广泛用作体脂百分比（%BF）的替代指标。BMI无法区分瘦体重和脂肪量，在儿童中，%BF与BMI之间的横断面关系会随年龄和性别而变化。
虽然男孩和女孩从8岁到12岁期间BMI随年龄呈线性增加，但%BF在10岁至12岁之间趋于平稳。对儿童的重复测量显示，从8岁到10岁再到12岁，对于任何给定的BMI，%BF都有系统性下降。由于BMI的变化不能准确反映%BF的变化，因此在该年龄组的纵向研究中应避免将其用作%BF的替代指标。
体重指数（BMI，kg/m²）通常用作儿童肥胖的指标，但由于其无法区分瘦体重和脂肪量的变化，在儿童纵向研究中的应用需要仔细考虑。
探讨BMI作为儿童纵向研究中体脂百分比（%BF）替代指标的适用性。
在这项纵向研究中，对健康的澳大利亚儿童（256名女孩和278名男孩）在8.0岁（标准差0.3）、10.0岁和12.0岁时通过双能X线吸收法测量身高、体重和体脂百分比（%BF）。
%BF和BMI均值的变化模式不同（P<0.001）。虽然平均BMI从8岁到12岁呈线性增加，但%BF在10岁至12岁之间没有变化。男孩和女孩中%BF与BMI之间的关系是曲线的，且随年龄（P<0.001）和性别（P<0.001）而变化；随着儿童年龄增长，任何给定的BMI对应的%BF较低。
考虑到10岁至12岁之间%BF和BMI时间模式的差异，在儿童纵向研究中，将BMI以绝对形式或年龄和性别标准化形式用作%BF的替代指标存在问题。
