Children who are relatively tall may be more likely than their shorter peers to become overweight young adults, a study published Tuesday suggests.
The study, which followed 2,800 U.S. children, found that those who were both tall and overweight at age 8 were at greatest risk of being overweight or obese around the age of 18.
But even among children who were within the normal weight range, those who were relatively tall were more likely to be overweight by young adulthood.
It's well known that overweight children often become overweight adults. However, the new findings, published in the American Journal of Preventive Medicine, suggest that extra height also puts some kids at risk for extra pounds in the long term.
This may be out of sync with what a lot of parents and doctors hope - namely, that taller children who are a bit heavy will keep getting taller while weight gain will slow — basically allowing them to "outgrow" their extra pounds.
Based on the current findings, extra height can instead be a liability. But it is not clear why that is, said lead researcher Dr. Steven Stovitz, an associate professor of family medicine and community health at the University of Minnesota in Minneapolis.
It's likely, though unproven, he told Reuters Health, that in some children, taller height is a sign of "advanced skeletal maturity," rather than a genetic predisposition toward being tall.
Advanced skeletal maturity essentially means that a child is moving toward his or her ultimate adult height more quickly compared with shorter kids. At a certain point, weight gain continues, but the rate of vertical growth slows down.
That results in an increase in the child's body mass index (BMI) — a measure of weight in relation to height — and a higher risk of excess pounds and obesity.
The findings are based on 2,802 students whose weight and height were measured in 3rd grade and again in 12th grade. One-quarter were overweight or obese in 3rd grade, as were nearly 36 percent as high school seniors.
Overall, the study found, the odds of becoming an overweight young adult were greatest among overweight 3rd graders who were in the top 25th percentile for height — meaning they were taller than three-quarters of their same-sex peers.
These children had an 85 percent chance of still being overweight as high school seniors. Those odds were 67 percent among overweight children who were in the bottom 25th percentile for height.
Similarly, among normal-weight 3rd grade students, the tallest kids had a 25 percent probability of becoming overweight by 12th grade. That figure was 17 percent among the shortest children.
According to Stovitz, the findings may be most relevant to parents who are not tall but have a child who is — as that height may be a sign of advanced skeletal maturity. He noted that while all parents should try to ensure their children are eating healthfully and getting regular exercise, it may be particularly important in these cases.
When a child has two tall parents, Stovitz said, the extra vertical inches are probably just a sign that he or she will be a tall adult.