The widespread use of Body Max Index (BMI) to measure childhood obesity in the UK may have misclassified children from certain ethnic minorities as obese, according to a new study.
Researchers from St George’s, University of London and University College London, claim their work “completely changes the current understanding of the link between ethnicity and weight status in young people”.
The study, funded by the British Heart Foundation and the National Institute of Health Research (NIHR), found that British children from South Asian backgrounds have the highest levels of obesity out of any group - when previous studies have suggested that black children have the highest levels of childhood obesity.
Dr Mike Knapton, associate medical director at the BHF, said: “This research suggests a large number of South Asian and black children in the UK are being misclassified into incorrect weight categories, and may be getting inappropriate health advice.”
BMI is the standard measurement of weight classification used by NHS doctors, but according to the researchers this measurement underestimates obesity levels in South Asian children by around 10% and overestimates levels in black children by around the same amount.
They found that more than 50% of all South Asian boys and two in five girls were overweight or obese by the time they left primary school.
This has the potential to have a huge impact as, of the 3.7 million children of compulsory school age in state-funded primary education, around 330,000 are of South Asian ethnic origin and 210,000 of African origin.
Mohammed Hudda, lead author of the study said: “After adjusting BMI to allow for ethnicity, we’ve found extremely high levels of overweight and obesity among South Asian children, which were not apparent using unadjusted BMI.
“Black children – other than older girls – had lower levels of overweight and obesity than previously demonstrated, which is a change from the conventional picture,” said Hudda.
“Most of us know that BMI has its limitations but the extent of its inaccuracy in children of ethnic minority backgrounds is now becoming more apparent.”
Not only is this frustrating for parents who are being giving wrong information, but the researchers suggest it could also be dangerous for children who are not given appropriate medical advice.
Especially “given the higher risks of type 2 diabetes and cardiovascular diseases in the long-term among UK South Asians from childhood”.
Knapton said: “Accurately identifying children who are overweight or obese is critical in ensuring they and their parents are given the right information and support to reduce the risk of diabetes and heart disease in later life. This is equally important for children who are underweight.”
In October it was reported that the rate of childhood obesity has plateaued in the UK over the last 10 years.
The figures, released as part of a large-scale report published in The Lancet on Tuesday 10 October, showed the number of obese children and adolescents worldwide has increased 10-fold between 1975 and 2016.