Will a new classification system dramatically alter our perception of the current state of overweight and obesity in kids? Researchers say traditional BMI measurement is NOT the best way to measure body fat…
Waist-to-height much more accurate than BMI when
classifying kids and teens as overweight or obese…
BMI already ‘in play’…
‘BMI’ stands for Body Mass Index. The US Nationl Institutes of Health define it as, “a measure of body fat based on height and weight that applies to adult men and women.”
It’s been considered the default ‘standard’ for evaluating a person’s overweight or obesity level. However, BMI does not distinguish muscle mass from fat mass, and may misclassify children as overweight.
And as of last year, BMI had begun to lose traction, as a standard, to a new measurement based on height-to-waist circumference.
How does this affect perception?
While medical practitioners already knew that BMI was not reliable when evaluating overweight or obesity in children. Researchers wanted to see just much more accurate the new system is.
What they did
A team of researchers from University of Eastern Finland (UEF) wanted to teat this hypothesis with a view to recalculating, more accurately, the current level of childhood and teen overweight and obesity around the world.
The team used data from a long-term follow-up study of some 7,600 British kids who were followed from ages 9 through 24.
Researchers analysed raw data from the survey to calculate both BMI-based and Height-to-waist ratio measures of body fat.
What they found
Of the 1,431 children classified as BMI-overweight at age 9 years, 25 percent had waist-to-height ratio classified as ‘high fat’, 11 percent had waist-to-height ratio ‘excess fat’, and 64 percent had waist-to-height ratio ‘normal fat’ according to the cutpoints used in the study.
However, of the 517 children classified as having Waist-to-height ratio ‘high fat’, 70 percent were BMI-overweight, 24 percent had BMI-obesity, and only 6 percent had normal BMI. That’s a pretty high level of disagreement between the two systems of measurement.
An extremely accurate lab process for measuring body fat confirmed that the Waist-to-height method was much more accurate than BMI.
The takeaway
“Waist-to-height ratio is an affordable and universally accessible, accurate and precise tool for detecting high and excess fat in children and adolescents,” says Andrew Agbaje, a physician and associate professor (docent) of Clinical Epidemiology and Child Health at the University of Eastern Finland.
“Overweight and obesity in children and adolescents should not be diagnosed with BMI alone but could be confirmed with waist-to-height ratio,” Agbaje concludes.
My take
In plain English, Body Mass Index (BMI) was found to be almost three times more likely to misclassify children as overweight than waist-circumference-to-height ratio.
That casts a dramatic new light on numbers we reported in this space just a week or two ago, that suggested more than 1 in every 3 kids would be overweight or obese by 2050.
Even adjusting for the new ‘standard’, the numbers remain troubling. But not as apocalyptic as ‘1 in 3’. Bottom line” The problems remain and action still needs to be taken NOW, to prevent a future obesity catastrophe!
~ Maggie J.