BMI found outdated for childhood obesity measurement in Bristol study
A groundbreaking study hailing from Bristol has shed new light on the efficacy of current methods used to assess childhood obesity, proposing a shift towards a more precise alternative. This research scrutinises the longstanding reliance on Body Mass Index (BMI) for evaluating obesity in children, suggesting that the waist-to-height ratio (WHtR) could serve as a superior metric.
The comprehensive analysis spanned over 15 years and delved into the health metrics of 7,237 children, each nine years of age, revealing significant insights. These findings challenge the existing guidelines that favour BMI as the standard obesity measure, underlining the urgent need for more accurate obesity detection in paediatric health.
Published in the prestigious journal Paediatric Research, this study is a component of the expansive Children of the 90s project, drawing attention to the escalating obesity rates amongst 10 and 11-year-olds in England, a surge notably exacerbated by the Covid pandemic and yet to recede to pre-pandemic figures.
Professor Julian Hamilton-Shield, a consultant paediatrician at the Bristol Royal Hospital for Children and a leading figure in the study, voiced concerns over the increasing prevalence of severe obesity and its complications observed in his weight management clinic. “The uptick in severe obesity levels and its attendant severe complications underscores the necessity for reliable measures that offer a clearer insight into an individual’s health status,” stated Prof Hamilton-Shield.
The research team scrutinised BMI data sourced from the government’s National Child Measurement Programme, which annually assesses approximately a million Year 6 students across England. While BMI has been a cornerstone in determining healthy weight parameters, offering a simple and quick assessment method based on height and weight, its limitations are becoming increasingly apparent. Specifically, BMI fails to account for body frame variations or muscle mass, rendering it an incomplete measure of body fat.
This limitation is particularly poignant when considering that BMI might categorise individuals with significant muscle mass, such as rugby players, as having obesity, highlighting its outdated nature. In contrast, the study, conducted in collaboration with researchers from the University of Bristol, the University of Exeter, and the University of Eastern Finland, advocates for the WHtR as a viable replacement for BMI. This method promises a more accurate assessment of excess fat mass in children and adolescents.
Professor Andrew Agbaje, the lead author of the study, emphasised the practicality and effectiveness of the waist circumference-to-height ratio. “Utilising just a measuring tape, we can accurately identify eight out of ten children who genuinely have obesity. Furthermore, this method allows us to correctly recognise 93 out of 100 individuals who, despite being muscular, would be mistakenly classified as overweight or having obesity by BMI standards,” Prof Agbaje explained.
He further highlighted that unlike BMI, which fluctuates with age and sex, the waist-to-height ratio remains consistent, irrespective of these variables. This finding underscores the potential of WHtR to revolutionise how childhood obesity is measured, offering a more nuanced understanding of body composition and facilitating the identification of true obesity, thus enabling more targeted and effective interventions.
