重庆城区正常体重学生和超重学生的体脂含量比较

Calculation of the body fat content in overweight students and normal weight students living in urban Chongqing

【目的】比较重庆市正常体重学生和超重学生的体脂推算值，分析体质指数（body mass index，BMI）和体脂百分比（percent body fat，PBF％）的相互关系，探讨不同肥胖筛查标准的一致性，为国内儿童肥胖判断标准的完善提供线索。【方法】以WHO的身高别体重（WFH）标准筛出超重学生844名，并按1：2配对选择了正常体重学生1688名。通过测量学生的身高、体重、肱三头肌和肩胛下皮褶厚度，计算BMI，并推算PBF。【结果】1）7～18岁每个年龄段的超重男生和女生的BMI均值和PBF中位数均分别显著高于同龄正常体重的男生和女生的对应值（P均〈0．001）；2）PBF与BMI的偏相关系数r为0．397（P〈0．001）。多元线性回归分析显示：PBF与性别（男=1，女=2）、BMI正相关，与是否超重（超重=1，正常=2）、年龄负相关（R2=0．578，P〈0．001）；3）与中国肥胖工作组WGOC公布的BMI切点标准相比，协作组推荐的PBF判断标准的特异度为83．0％，灵敏度为82．9％。【结论】重庆城区超重学生和正常学生的脂肪推算值差异显著。PBF受多种因素影响，与BMI呈低度相关。直接测量学生的体内脂肪，建立本国的PBF筛查标准，联合BMI切点标准可能更有利于学生肥胖的准确诊断。

[Objective] To reflect the body fat content by using body mass index （BMI） and percentage body fat （PBF%） calculated between the overweight students and normal weight students aged 7 - 18 years living in urban Chongqing, and analyze the relation of BMI and PBF in the students , and explore the consistence of different overweight standards, so as to provide some clues for improving the diagnose level of student overweight. [Methods] According to the weight for height standard from WHO（WFH）, 844 overweight students and 1 688 healthy weight children （matched with 1 ： 2） were recruited for this study, whose weight, height, triceps skinfold and subseapular skinfold were measured with international authropometry. The body fat percent （PBF%） and the BMI were calculated. [ Results] 1 ）The BMI mean and PBF% median in overweight girls and boys aged 7-18 years were significantly higher than those in normal weight girls and boys at the same age respectively（P〈 0. 001）. 2）BMI was found closely correlated with PBF% in the students when age, sex and group were controlled （r = 0. 397, P〈0. 001 ）. Moreover, linear regression analysis revealed that sex （male= 1, female= 2）and BMI were significantly positively correlated with PBF%, while age and group（overweight = 1, normal=2） negatively with PBF%（R2 =0. 578,P〈0. 001）. 3） Compared with the BMI cutoff values of Working Group on Obesity in China （WGOC） ,the specificity and sensitivity of the PBF cutoff values was 83.0% and 82.9%. [Conclusions] There are significant differences in body fat content calculated of overweight students and normal weight students and there is the low correlation between BMI and PBF%. To measure body fat directly and establish Chinese student PBF overweight screening standard and combine the BMI cutoff values may be contribute to improve thediagnose level of overweight screening.