Study on Age-and Sex-Specific Body Composition of Children in Beijing Area / 实用儿科临床杂志

ABSTRACT

Objective To explore the age-and sex-specific body composition of normal children in Beijing area.Metheds The subjects were a total of 587 children of 6-14 years old,who were recruited from Beijing schools.All of them had relative weight within normal range(80%～120%),and no chronic disease.The relative weight was obtained,according to standard weight,using the follo-(wing) formula relative weight(%)=(body weight/standard weight) ?100.Body compositions were estimated with a bioelectrical impedance analyser,which had been proved to be reliable and valid for determining the percentage of body fat.Results Not only fat free mass(FFM) but also fat mass(FM) increased monotonically with age in both sexes.FFM was higher in boys than that in girls at all ages.FM was significantly higher in girls than that in boys aged 6 to 8 years old;however,there was no significant difference for FM between sexes aged 9-14 years old.Patterns of change in mean ratio of body fat(%BF),with age differed by sex.Percent age of BF was significantly higher in girls than that in boys at all ages except at 10 and 11 years old. In boys,%BF increased with age,while in girls it remained nearly constant from age 6 to 10 years old,and gradually increased from age 10 to 14 years old.Body mass index(BMI) increased steadily with age in both sexes,and boys had consistently higher BMI than girls.In boys,the increase in BMI was steeper from age 10 to 14 years old.Even in the subjects with BMI