We know that although frequently used to diagnose overweight or obesity in adults, thebody mass index (BMI) is not a reliable measure in children. Thus, in June 2014, an American study carried out on 50,000 young people aged 4 to 18 had shown that there was a “margin of error” of approximately 25% (source). It is therefore impossible to declare that a child or a baby is in overweight or in a situation of obesity from this measurement alone …
Except that according to a recent study by the Children’s Hospital of Philadelphia (CHOP, in the United States), the use of BMI in toddlers would still make it possible to predict certain risks ofobesity. A tool which, according to the researchers, is even more reliable than the growth chart …
To verify this hypothesis, the scientists worked on the medical records of 74,000 American children, whom they followed for 5 years (from 2006 to 2011). Results ? 31% of children aged 2 months with a BMI qualified as “high” by researchers were obese by the age of 2 years. And 47% of 2-month-old babies with “very high” BMIs were obese by 2 years.
At 6 months, the BMI and the growth curve would also be reliable
“We noticed that at the age of 2 months, a high BMI could indicate an equally high risk of obesity from the age of 2 years” summarizes Babette S. Zemel, main author of this work published in the specialized journal Pediatrics. However, the researchers continue, around the age of 6 months, the growth curve and BMI show the same reliability.
As a reminder, the body mass index is calculated by dividing the weight (in kilograms) by the height (in meters), the latter being squared. This measurement is not completely reliable among pregnant women and great athletes, since it does not differentiate muscle mass from fat mass … In general, health professionals prefer to use impedancemetry, a much more precise tool that only allows fat mass to be evaluated.
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