Preschool weight gain confers highest risk for teenage obesity

By Eleanor McDermid
N Engl J Med 2018; 379: 1303–1312, 1371–1372
01 November 2018

medwireNews: Children who start to gain weight in their preschool years are at the highest risk of being obese in adolescence, shows a study in The New England Journal of Medicine.

“The probability that young children who are obese will return to a normal weight in adolescence appears to be less than 20% and decreases further with age”, say the researchers, who also stress that “most obese adolescents become obese adults.”

Antje Körner (University Hospital for Children and Adolescents, Leipzig, Germany) and team tracked the BMIs of 51,505 children from infancy to adolescence (between 15.0 and 18.9 years).

At the age of 2 years, 3.3% of the children were obese, but around 50% of these children had returned to a normal BMI by adolescence. However, of the 4.1% who were obese at the age of 3 years, almost 90% were overweight or obese in adolescence.

Study participants who were overweight or obese as adolescents had an increasing BMI throughout childhood, but the largest acceleration occurred between the ages of 2 and 6 years. These children had a 28.6% likelihood of being overweight or obese during adolescence, compared with a 20.0% likelihood among those whose BMI remained stable during this time.

By contrast, the risk for later overweight or obesity in children with a marked BMI increase during their school years was no higher than for those with stable weight during their preschool years. These BMI relationships were seen in both boys and girls, the team notes.

Editorialist Michael Freemark (Duke University Medical Center, Durham, North Carolina, USA) describes the findings as “new and important”.

He writes: “The current study was not designed to determine whether exaggerated weight gain in early childhood is a cause of subsequent obesity or a marker of previous, inherent, or future risk of obesity. Nevertheless, the identification of a critical window for predicting childhood weight gain provides an opportunity for intervention to prevent obesity in children at risk.”

He says that the effects of nutritional counselling for families of preschool children with accelerating BMIs should be tested in a clinical trial, and further suggests that “[c]ounseling could be applied preemptively for families in which the parents are overweight, particularly if there is a history of maternal diabetes or smoking.”

Both being large for gestational age at birth and having an overweight or obese mother were associated with an increased likelihood of children being overweight or obese in adolescence. For example, 43.7% of large for gestational age children became overweight or obese, compared with less than 30% of other children.

But even allowing for this, the association between preschool BMI acceleration and adolescent overweight or obesity still applied.

Körner and team suggest that tracking of early-life BMI might be applied particularly to these at-risk groups. They add that it is “important for health care professionals, educational staff, and parents to become more sensitive to this critical time period.”

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