Ethnic and gender differences in body fat in British schoolchildren as measured by DXA.

BACKGROUND

There are known to be ethnic differences in body composition in adults which are related to ethnic differences in adult disease.

OBJECTIVES

To evaluate gender and ethnic differences in percentage body fat in British schoolchildren and to compare these differences with classification of obesity using body mass index (BMI) criteria.

DESIGN

A cross-sectional study of 1251 healthy children and adolescents aged 5-18 years from white, South Asian and African-Caribbean ethnic groups. Percentage body fat was determined by dual x ray absorptiometry and the subjects classified using BMI criteria for overweight and obesity.

RESULTS

Significant gender differences in percentage body fat were seen, with girls having higher values from the age of 5 years. Girls had 3.8% higher percentage body fat at 5 years of age increasing to 12.9% at 18 years of age. Significant ethnic differences were found, with South Asian girls and boys having the highest percentage body fat from 5 and 7 years of age, respectively. These differences increased with age, being most significant in the teenage years. Although South Asian girls and boys were over-represented in the group containing children with more than 25% body fat (p<0.0001, chi2 test), African-Caribbean subjects were more likely to be classified as obese using BMI criteria.

CONCLUSIONS

There are clear gender and ethnic differences in percentage body fat in British schoolchildren which may relate to known differences in the risk of type 2 diabetes in adolescence and adulthood. BMI criteria for defining overweight and obesity do not accurately identify ethnic differences in body fat.