Select Research is building the BVI as a spin-off from its work with Next, Monsoon, Asda and others on the National Childrenswear Survey.

At least 6,000 children aged 14-17 will have taken part in the study by the time of its completion next year, each having had their body shapes analysed using 3D scanners.

The retailers will use the results of the research to adjust their clothing sizes where necessary, but Select recently received the blessing of its partners to take data from the study and develop the BVI.

Agency boss Richard Barnes (pictured) said the firm is currently in talks aimed at getting the index adopted by the UK government, which has made a commitment to reverse the trend in obesity and excess weight among children by 2020 and to bring it back down to levels last seen in the year 2000.

Barnes said current measures of childhood obesity are based on the body mass index, which is a measure of height against weight.

BMI is widely considered to be a flawed measure of obesity – not least in the fact that muscle weighs more than fat. It is, however, a more reliable measure for adults, where height is constant, than it is for children, who are still growing. To get round this problem, Select’s index will be based on differences in “weight distribution”, said Barnes.

The company developed a BVI for adults in 2007, which followed on from its work on the National Sizing Survey in 2004.