A collaboration between Finnish and British researchers found that body mass index (BMI) was almost three times more likely to classify children as overweight than waist circumference-to-height ratio/
Their study confirms previous recommendations by the UK National Institute for Health and Care Excellence that waist-to-height ratio be used as a tool to predict health risks associated with central adiposity in children.
Published in Obesity and Endocrinology, the study was based on collaboration between the University of Eastern Finland and the Universities of Bristol and Exeter in the UK.
BMI and weight-to-height indices are universally employed as markers of childhood obesity, but BMI does not distinguish muscle mass from fat mass, and may misclassify children as overweight.
Recently, the Lancet Commission on Obesity and the European Association for the Study of Obesity (EASO) also recommended that obesity in adults should not be diagnosed with BMI alone but confirmed with another measure, like waist-to-height ratio.
The present study is the largest follow-up paediatric study in the world comparing BMI and waist-to-height ratio. It included 7 600 children drawn from the University of Bristol’s Children of the 90s cohort who were followed up from ages nine until 24 years.
Of the 1 431 children classified as BMI-overweight at nine, 25% had waist-to-height ratio high fat, 11% had waist-to-height ratio excess fat, and 64% had waist-to-height ratio normal fat, according to the cut-points used in the study.
However, of the 517 children classified as having waist-to-height ratio high fat, 70% were BMI-overweight, 24% had BMI-obesity, and only 6% had normal BMI.
Dual-energy X-ray absorptiometry (DEXA) is considered the gold-standard for accurate body fat measure, however, this expensive device is not universally available in primary health care. It was previously reported from the same data that waist-to-height ratio can assess body fat to a maximum of 85% accuracy compared to DEXA results.
The waist-to-height ratio cut-points for high, excess and normal body fat used in this study were developed from earlier results in the same children and adolescents.
In the present study, these waist-to-height ratio cut-points were also externally validated for type 2 diabetes prediction in 3 329 US adults. Waist-to-height ratio high fat was associated with higher odds of pre-diabetes, while waist-to-height ratio excess fat predicted higher odds of type 2 diabetes.
“Waist-to-height ratio is an affordable and universally accessible, accurate and precise tool for detecting high and excess fat in children and adolescents,” said Andrew Agbaje, physician and associate professor (docent) of Clinical Epidemiology and Child Health at the University of Eastern Finland.
His earlier research has also shown that waist-to-height ratio predicts both total body adiposity and central adiposity.
“Overweight and obese children and adolescents should not be diagnosed with BMI alone but could be confirmed with waist-to-height ratio where a DEXA scan is lacking,” Agbaje added.
Study details
BMI triples overweight prevalence in 7600 children compared with waist-to-height ratio: The ALSPAC Study
Andrew Agbaj
Published in Obesity and Endocrinology on 14 February 2025
Abstract
Objective
Waist circumference-to-height ratio (WHtR) is a highly sensitive and specific surrogate marker of excess total body adiposity and central adiposity (adiposopathy). This study examined the prevalence of body mass index (BMI) categories in relation to newly developed WHtR cut points (Agbaje WHtR cutoff) in the paediatric population. The WHtR estimated fat mass categories predictive ability to detect the risk of pre-diabetes and type 2 diabetes was examined in an adult population.
Design
A prospective birth cohort study in the UK externally validated with a nationwide survey data from the US.
Methods
Altogether, 7 600 9-year-old children from the Avon Longitudinal Study of Parents and Children, UK birth cohort were included. Body mass index and WHtR were assessed at ages 9, 15, and 24 years. Waist circumference-to-height ratio cut points are <0.40 as low fat; 0.40 to <0.50 in males as normal fat; 0.40 to <0.51 in females as normal fat; 0.50 to <0.53 in males as high fat (adiposopathy grade 1); 0.51 to <0.54 in females as high fat; >0.53 in males as excess fat (adiposopathy grade 2), and >0.54 in females as excess fat. From the National Health and Nutrition Examination Survey (2021 to 2023 cycle), 3329 US participants with a mean (SD) age of 49 (20.3) years who had glycohaemoglobin and fasting plasma glucose were included.
Results
Body mass index overestimated the prevalence of overweight by 2.8-fold in childhood, 2.3-fold in adolescence, and 2.6-fold in young adulthood compared with WHtR. Of 1431 children classified as BMI overweight, 25% had WHtR high fat, 11% had WHtR excess fat, and 64% had WHtR normal fat. However, of the 517 children classified as having WHtR high fat, 69.8% were BMI overweight and 24% had BMI obesity, while only 6% had normal BMI. Waist circumference-to-height ratio high fat was associated with higher odds of pre-diabetes [odds ratio 2.36 (95% CI, 1.10-5.10), P = .028]. Waist circumference-to-height ratio excess fat was associated with higher odds of type 2 diabetes [6.08 (2.84-13.01), P < .001].
Conclusions
Waist circumference-to-height ratio can be universally adopted for preventing, diagnosing, and managing excess adiposity (adiposopathy) in paediatrics.
The Lancet Commission – Definition and diagnostic criteria of clinical obesity (Open access)
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