Ethnicity, socio-economic status, overweight and underweight in east London adolescents

Background. The developed world is experiencing an 'epidemic' of childhood obesity but little is known about the prevalence of obesity, or underweight, amongst adolescents from minority ethnic groups in the UK. An understanding of the prevalence of obesity and overweight in these populations is important since some ethnic groups may be particularly vulnerable to the adverse health effects associated with obesity. Study Objectives. To examine levels of extreme obesity, obesity, overweight and underweight amongst a representative sample of adolescents from different ethnic groups in East London and to explore the association between socio-economic status and body mass index (BMI). Design. A school-based survey of adolescents aged 11-14. Obesity and overweight were estimated using the 1990 UK growth reference (UK 90) and the International Obesity Task Force (IOTF) cut-off points. Extreme obesity was defined as a BMI more than three SD above the UK 90 mean. Underweight was examined by looking at those with a BMI below the 15th or the 5th UK 90 percentiles. Main Results. A total of 2,482 adolescents were surveyed (response rate 84%), 73% from non-white ethnic groups. Although there were significant differences in BMI between ethnic groups, high levels of overweight were seen in all ethnic groups. More than one-third were overweight and one-fifth were obese using the UK 90; and over a quarter were overweight and almost one-tenth were obese using the IOTF cut-offs. Two per cent were extremely obese. Indian males were at higher risk of being overweight than white British males. The Prevalence of obesity and overweight was similar in white British and Bangladeshi males. Overall the prevalence of underweight was slightly lower than that predicted by the UK 90, but South Asian ethnic groups, especially males, had a higher prevalence of underweight than other groups. No associations between BMI and measures of socio-economic status were found in this relatively deprived population. Conclusions. The 'epidemic' of childhood obesity observed in the UK involves adolescents from all ethnic groups, although there are some differences between ethnic groups in the prevalence of overweight. Indian males appear to be at increased risk of being overweight. There is no evidence of a simultaneous increase in underweight amongst this population overall, but Bangladeshi, Indian and Pakistani boys appear to be at increased risk of being underweight.