Children who are obese by age 5 may remain that way for the rest of their lives, according to a New England Journal of Medicine study, which surveyed nearly 8,000 children.
The study, which was released Thursday, revealed that a third of the children who were overweight in kindergarten were obese by the time they reached the eighth grade. Virtually every child who was already obese remained so for the duration of the study.
While very few obese and some overweight kindergartners managed to drop the extra pounds, some children with normal weights also became obese during the study, which followed the children from kindergarten to eighth grade. As each year passed the chances of an obese or overweight child losing the weight decreased.
Furthermore, kids who were overweight entering kindergarten had a 32 percent chance of becoming obese, four times as likely as a normal-weight child, Solveig Cunningham, the lead author of the study and an assistant professor at Emory University’s Rollins School of Public Health, told Al Jazeera.
When the children in the study started kindergarten, 12 percent were obese and 15 percent were overweight. By the time they reached eighth grade, 21 percent were obese and 17 percent were overweight.
From age 5 to 14, 10 percent of the girls in the study and almost 14 percent of boys became obese. And nearly half of the kids who started kindergarten overweight became obese teens, according to the study.
"We’ve been studying childhood obesity for quite a while, but we realized in looking at the numbers that we actually know very little about the incidence of obesity — that is, how children who are obese become obese — and so that’s why we decided to take this approach," Cunningham told Al Jazeera America.
The work also shows the need for parents, doctors, preschools and even day care centers to be involved in monitoring obesity, Dr. Stephen Daniels, a University of Colorado pediatrician and a spokesman for the American Heart Association, told The Associated Press.
"You can change your fate by things that you do early in life," with more exercise and eating a healthy diet, Daniels told the AP. "Once it occurs, obesity is really hard to treat. So the idea is we should really work hard to prevent it."
Socioeconomic factors play a part, too, with the wealthiest children having the lowest risk of developing obesity, and black and Hispanic children having the highest risk. But by the time the children reach kindergarten those effects are significantly diminished, according to the study.
Some experts were surprised by the study's results. The findings, they said, have the potential to alter the way people approach the growing obesity epidemic in the United States. The report suggests that prevention efforts must begin much earlier than previously thought and should be targeted to those with the highest risk.
Earlier studies on obesity have revealed the number of children who are obese or overweight at various ages, but none have tracked the changes in weight over time until now.
"What is striking is the relative decrease in incidence after that initial blast" of obesity that occurs by age 5, Dr. Jeffrey P. Koplan, vice president of the Emory Global Health Institute in Atlanta, told The New York Times. "It is almost as if, if you can make it to kindergarten without the weight, your chances are immensely better."
The study does not explain why children remain obese if they reach kindergarten in that condition, but the research team believes it may be a combination of factors such as genetics and an atmosphere that promotes overeating.
"Kids who are overweight at one point are much more likely to be overweight at another point," Cunningham said.
"This study gives us an opportunity to do something about childhood obesity by focusing on the first five years," she said. "It really reminds us that those first five years are really important, and this study adds to that also, basically saying let's really be careful promoting healthy weight in the first five years."