Kids who are overweight or obese at five years old tend to stay that way into their teen years – and possibly beyond – according to a new study in the New England Journal of Medicine. There’s some evidence that the childhood obesity crisis has improved or at least leveled off in the last decade or so. But the new research suggested that it’s still a serious concern. And it pointed to one reality in particular: Weight problems begin at a much earlier age than we’d thought, which means that weight loss “interventions” will have to be shifted to reflect this.
The new study tracked 7,700 kids from the time they were in kindergarten through their 8th grade year. Their body mass index was calculated and converted to a percentage: Kids who are between the 5th and and 85th percentiles are considered normal weight. Between 85th and 95th percentile is considered overweight, and above the 95th is considered obese.
Kids who at age 5 were overweight or obese, which was about 15% and 12.4%, respectively, had far greater chances of remaining that way into their teen years. And the ones who were overweight at age 5 had a four-fold greater risk of being obese at age 14.
Put another way, half of the kids who were obese at age 14 had been in that 15% of overweight 5-year olds.
And it doesn’t seem to take much excess weight to increase a child’s odds of becoming overweight. About 87% of the kids who were obese in the eighth grade had been just somewhere over the 50th percentile as kindergarteners, which suggests that being anywhere above the midpoint of “normal” at age 5 can predispose children for obesity in the years to come.
The study also illustrated how difficult it is to lose weight in childhood: Only 13% of the kids who were normal weight in 8th grade had been overweight in kindergarten.
Childhood obesity is clearly the result of a combination of variables: Genetic predisposition, intrauterine factors, and the behavioral stuff that’s going on in the household (i.e., kids mimic the eating habits they see at home). The authors especially stress the prenatal factors– for example, a much higher number of high-birth-weight babies (36%) go on to be overweight teens, which suggests that a considerable portion of weight is determined before a child is even born.
Since the results suggest that a “substantial component of childhood obesity is established by the age of 5 years,” the team wonder, of course, how this trajectory can be shifted. Focusing efforts on kids who are already overweight or obese at a very young age, perhaps in the preschool years, is really the key, they say. But what that consists of is unclear. Some studies have shown early weight interventions to be effective, while others have been less encouraging. And health insurance may be reluctant to cover such interventions.
But hopefully the study will shift our focus from the school-age years to the preschool years. And hopefully this will be reflected in public health campaigns and pediatricians’ offices.
The study didn’t track what happens to the kids after age 14 – but if the U.S. adult population is any indication, the kids in this study will, unfortunately, continue along a similar course.