Children who are tall for their age at higher risk of obesity, new study shows

A new study has found that children below the age of 12 who are relatively tall for their age have an increased risk of developing obesity.

The health records of 2.8 million children were examined as part of the study, published in the research journal Obesity. Participants were initially examined between two to 13 years of age, and then re-examined an average of four years later, but up to 13 years later.

Researchers found that children who were taller than average during the initial examination were more likely to have higher body mass index (BMI) than shorter children on reexamination.

Among the thinnest children at the start, the prevalence of obesity at the second exam increased fivefold in the tallest children (3.1 per cent) compared to the shortest (0.6 per cent). Among the heaviest children at the start, the respective prevalence rates of obesity were 89.5 per cent versus 53.4 per cent.

David S. Freedman, of the Centres for Disease Control and Prevention and lead author of the study, said: “As about half of this association is independent of the initial body mass index of the child, the use of height may be a simple way to more accurately classify which children will become obese.”

The association between taller children and obesity at the second exam was strongest in children who were initially examined when they were younger than seven years old.

2,911 children in the study who were followed from childhood to adulthood who were measured at a height at or above the 95th percentile were more than twice as likely to have an adult BMI above 30kg per square meter.

Having an “excess caloric intake” as a child may accelerate their height, and obese children who lose weight have been found to have a “deceleration in height growth”, said the study, suggesting that serving sizes may cause an increase in BMI, skeletal growth and maturation in childhood.

Although childhood height and obesity have been correlated by previous studies, this new study reinforces that taller children are more likely to have higher BMI.

The authors recommend that health professionals should “recognise that greater childhood height-for-age before the age of 12 years may help to identify children who are at increased risk for developing obesity”.