This article is more than 5 years old. Information may no longer be current.

Waist-to-height ratio stronger identifier of obesity than BMI

Measuring an individual’s waist-to-height ratio is the most accurate method to predict their risk for obesity, according to a study published in PLoS One.

“The conventional measurement of obesity used by [general practitioners] is BMI,” Michelle G. Swainson, MSc, PhD, lead researcher of the study from Leeds Beckett University in England, said in a press release. “Although there are benefits to this method, there is concern that a lot of people are being classified as obese by BMI when they are not or are being missed by this classification when they need to be referred for help. This is most definitely the case when people have a ’normal’ BMI but high abdominal fat that is often dismissed. Whole-body fat percentage, and specifically [visceral adipose tissue] mass, are associated with health conditions including insulin resistance, type 2 diabetes and cardiovascular disease, but are not fully accounted for through BMI evaluation.”

“Carrying fat around the abdominal area has been shown to be an independent predictor of all-cause mortality in men and women,” she added. “Put simply, it is more important, especially for cardiometabolic conditions, that your belt notch goes down than the reading on the scales.”

Swainson and colleagues sought to improve how obesity is currently measured by comparing five anthropometric predictors of whole-body fat percentage and visceral adipose tissue mass, as well as identify the best cut-point predictors for these measures. They enrolled 81 adults (40 women; mean age, 38.4 years; 94% Caucasian) and calculated their BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio and waist-to-height ratio^0.5. To quantify whole-body fat percentage and visceral adipose tissue mass, the researchers performed total body dual energy X-ray absorptiometry with Corescan. They also conducted a linear regression analysis to determine the whole-body fat percentage and visceral adipose tissue mass for each anthropometric predictor.

The researchers found that in both men and women, the best predictor of whole-body fat percentage and visceral adipose tissue mass was waist-to-height ratio. Using whole-body fat data helped classify 36.5% more adults as obese than BMI. In addition, BMI was a poor predictor of whole-body fat percentage among both sexes; however, it was a reliable predictor of visceral adipose tissue mass among women. Conversely, for both measures, the waist-to-hip ratio was a weak predictor of obesity. The whole-body obesity cut-points predictors were 0.53 in men and 0.54 in women, while the abdominal obesity cut-point predictor was 0.59 for both men and women.

“Our [waist-to-height ratio] cut-points align broadly to current guidelines that adults and children should keep their waist circumference to less than half their height,” Swainson said. “In current clinical practice, it is common to calculate BMI for an indication of whole-body fat and waist circumference for abdominal obesity.”

“Our research has shown that [waist-to-height ratio] is a more accurate alternative to these two measures and also a more time-efficient measure,” she continued. “By introducing this alternative, and more accurate, measure into clinical settings, more men and women would potentially be referred to programs, such as weight management, to receive help in improving their health. We have also shown how these simple measurements may be used as surrogates by [general practitioners] and other health care professionals when [dual energy X-ray absorptiometry] scans are unavailable or inaccessible.”

“Even in a small sample of adults, our results provide further evidence that alternative measures are fundamental to the more accurate identification of obesity, therefore ensuring that individuals are referred to the most suitable therapeutic approach to reduce risk of obesity-related conditions,” she concluded. – by Alaina Tedesco

Disclosure: The authors report no relevant financial disclosures.