New research is casting doubt on a 42-year-old theory that has helped shape how doctors think about childhood body mass index, according to ScienceDaily.
The long-standing idea, known as “adiposity rebound,” says BMI falls after infancy and then rises again around age 6 because body fat is returning. But the new analysis suggests that later increase in BMI may instead come mostly from normal growth in muscle and other lean tissue.
The study was led by Professor Andrew Agbaje, a physician and associate professor of clinical epidemiology and child health at the University of Eastern Finland. It was presented at the European Congress on Obesity in Istanbul and published in The Journal of Nutrition.
To look more directly at body fat, Agbaje used waist circumference-to-height ratio, which the article says is a better marker of adiposity than BMI. In data from 2,410 multiracial children ages 2 to 19 in the U.S. National Health and Nutrition Examination Survey, BMI returned to its age 2 level by age 6, but the waist-to-height measure did not rebound in the same way.
According to the report, the findings could have implications for childhood health care because some physicians have treated the timing of BMI’s rise as an early warning sign. Agbaje argues the pattern may be a normal part of growth rather than a sign of disease.
