The use of the body mass index to determine whether a young person is obese may not tell the whole story regarding the prevalence of childhood obesity, a new study warns.
More than 25% of children between the ages of 4 and 18 were found to have an excess body fat percentage despite registering a BMI within the range of what is considered normal, according to a meta-analysis conducted by researchers at the Mayo Clinic and published online Tuesday in the journal Pediatric Obesity.
BMI, which uses a person’s height and weight to estimate body fat, is the most commonly used method for calculating whether a person is overweight or obese. While BMI was shown to accurately identify children who were actually obese, the formula was less effective in detecting kids who should have been considered obese based on their body fat percentage but had normal BMI.
“If we are using BMI to find out which children are obese, it works if the BMI is high, but what about the children who have a normal BMI but do have excess fat?” study senior author Dr. Francisco Lopez-Jimenez, director of preventive cardiology at the Mayo Clinic in Rochester, Minn., said in a written statement. “Those parents may get a false sense of reassurance that they do not need to focus on a better weight for their children.”
The analysis examined the findings of 37 studies that included more than 53,000 children and compared the performance of BMI to detect excess body fat with other methods used to determine obesity, such as skinfold thickness measurement and dual X-ray absorptiometry, which is primarily used to evaluate bone mineral density but has been found to have a high level of accuracy when measuring body composition and fat content.
The Centers for Disease Control and Prevention estimates that as many as 17% of U.S. children are obese and 32% are either overweight or obese. The rate of childhood obesity has more than doubled over the past 30 years, and has been linked to a rise in chronic diseases long associated with aging adults, such as heart disease, Type 2 diabetes and hypertension.
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