儿童青少年身体脂肪含量和非脂体重的变化分析

Analysis on the Changing of Body Fat Mass and Fat-free Mass in Child and Adolescent

目的:分析儿童、青少年身体脂肪含量(FM)和去脂全重(FFM)及其随年龄变化特点及性别差异。方法选择7～15岁体重正常的儿童180名,男、女及每个年龄组各约10名,采用双能 X 线吸收测量法(DEXA)测量身体成分。根据公式 FFMI(kg·m^2,去脂体重指数)=FFM(kg)/身高~2(m^2)和 FMI(kg·m^2,脂肪含量指数)=FM(kg)/身高~2(m^2),计算 FFMI 和 FMI。结果 7～13岁儿童 FM 及全身脂肪含量占体重百分比随年龄增加而增加,13岁以后有所下降,女高于男。7～15岁男、女儿童 FFMI 随年龄增加而增加,男生青春期 FFMI 增长加速,增加总量为女生的2倍,7～15岁男生 FMI 先增后降,女生则一直呈上升趋势,女生 FMI 增加总量为男生的2倍。男生身高与 FMI 相关性差,11～15岁男生的身高与 FFMI 呈显著性正相关。7～10岁女生身高与 FMI 呈显著性正相关,9～10岁女生的身高与 FFMI 呈显著性正相关(P<0.05)。男、女儿童的 BMI 与 FMI 均呈显著性正相关,男生相关系数大于女生。13～15岁男生和7～15岁女生的BMI 与 FFMI 呈显著性正相关(P<0.05)。结论青春期前后儿童脂肪含量及分布随年龄而变化,男女差异有显著性。男性脂肪向分布加速期发生在12岁,女性在10岁。男生 BMI 随年龄增长而增加,主要为 FFMI 的增加,尤其是青春期男生。女生 BMI 的增长为 FFMI 和 FMI 的同时增加。

Objectives To analyze the characteristics of body fat mass and fat-free mass in children and adolescents and their change with age and difference by gender.Methods Totally,180 healthy children and adolescents aged 7～15 years with normal body weight were selected for investigation,10 for each age-group in both boys and girls.Body fat mass and fat-free mass were measured by dual-energy x-ray absorptiometry(DEXA).Fat-free mass index(FFMI)and fat mass index(FMI)were calculated according to following equations:FFMI(kg·m^(-2))=FFM(kg)/height^2(m^2),and FMI(kg·m^(-2))=FM(kg)/height^2(m^2). Results Fat mass and body fat percentage increased with age in children from 7 to 13 years old and decreased after 13 years old. Girl's FM was higher than boy's.Both boy's and girl's FFMI increased with age between 7～15 years old and the increase of boy's FFMI accelerated during puberty,with a total increment of twice as girl's.At 7～15 years old,boy's FM!increased first and then decreased,while girl's increased all along during this phase.Total increment of girl's FMI was about twice as boy's.Body height poorly correlated with FM1 in boys,while it correlated with FFMI in boys at age of 11～15 years significantly(P<0.05).Body height correlated with FM1 in girls at age of 7～10 years and with FFMI at age of 9～10 years significantly(P<0.05).BMI correlated with FMI significantly both in boys and girls with a larger coefficient of correlation for boy's.BMI correlated significantly with FFMI for boys at 13-15 years old and girls aged 7～15 years,respectively(P<0.05).Conclusions Fat mass and fat-free mass,as well as their distribution,changed with age in childrenaround their puberty.There was significant difference in fat mass and fat-free mass between boys and girls.Acceleration phase for concentric distribution of fat mass was at age of 12 years in boys and 10 in girls.Boy's BMI increment with age mainly came from their FFM,especially in adolescent boys.While increment of BMi Jn girls attributed to both FFM and FM.