Using body mass index (BMI) alone as a screening tool for obesity may miss children with unhealthy levels of body fat, according to a study published Sept. 8 in the journal JAMA Pediatrics.
The study analyzed data from children who are participants in the Cameron County Hispanic Cohort (CCHC), a long-running population study based in Brownsville, Texas, and compared the results with data from the National Health and Nutrition Examination Survey.
The findings support including additional measures for body composition to identify children with excess body fat that puts them at higher risk for diabetes, heart disease and other chronic conditions.
“Our study emphasizes the need for improved early detection of excess body fat in children, particularly in communities with high rates of obesity-related illnesses. Early identification could allow for timely interventions to prevent lifelong health problems,” said Jennifer (Piper) Below, PhD, director of the Vanderbilt Genetics Institute and a senior author of the study.
The CCHC, founded in 2014 by study co-authors Susan Fisher-Hoch, MD, and Joseph McCormick, MD, is a group of 5,000 randomly recruited individuals from households on the U.S.-Mexico border. The population is 100% Latino and about 96% Mexican American.
In the current study, the researchers analyzed data from 183 CCHC participants ages 8-17 who had weight, height and waist circumference measurements, as well as DEXA analysis (dual-energy X-ray absorptiometry), which measures bone density, fat mass and lean mass. Excess body fat was defined as having one or more of the following conditions: elevated waist-to-height ratio, severe obesity based on BMI, or elevated fat mass index.
The investigators found that almost all children classified as obese by BMI had excess body fat, confirming BMI’s usefulness in detecting obesity. However, nearly one-third of children who were not classified as obese by BMI had excess body fat.
“While BMI is the most common tool for identifying childhood obesity, our new research study shows it overlooks nearly one-third of kids with unhealthy levels of body fat, especially in high-risk communities along the U.S.-Mexico border, underscoring the need for improved obesity screening in children,” said Kari North, PhD, Vice President of Border Health at UTHealth Houston School of Public Health in Brownsville and a senior author of the study.
The researchers found that participants with elevated fat mass index (determined by DEXA analysis) also had elevated waist-to-height ratio, suggesting that waist circumference measurements along with weight and height may be a practical, low-cost marker to confirm excess body fat among children.
Penny Gordon-Larsen, PhD, W.R. Kenan Jr. Distinguished Professor and vice chancellor for Research at the University of North Carolina at Chapel Hill, is also a senior author of the study. Other authors from Vanderbilt University Medical Center are Rashedeh Roshani, MS, and Elizabeth Frankel.
The research was funded in part by the National Institutes of Health (grants UL1TR000371, R01HL142302, R01DK122503 and R01DK139598).
