Reports of significant progress against child obesity in the United States have been premature, say the latest researchers to take a look at the data.
Overall child obesity rates are flat, and rates of severe obesity are rising, says a study published Monday by JAMA Pediatrics. And the idea that rates are plunging among preschoolers — heralded in a study and press release from the Centers for Disease Control and Prevention just weeks ago — did not stand up when researchers scrutinized a few extra years of data, says lead author Asheley Cockrell Skinner, assistant professor of pediatrics at the University of North Carolina School of Medicine.
Skinner says she and co-author Joseph Skelton, of Wake Forest University Baptist Medical Center, looked at the same data CDC used from the National Health and Nutrition Examination Survey. The CDC found preschool obesity rates fell from 14% in 2003-2004 to 8% in 2011-2012, a drop of 43%. Skinner and Skelton saw the same thing, but found rates of 10% to 11% in earlier surveys, dating to 1999 — making any long-term decline smaller and less likely to be significant, Skinner says.
Some researchers questioned the CDC's claim at the time, saying it was based on numbers that had gone up and down, and on reports from just a few hundred children each year. CDC cited additional evidence, including declines in preschoolers tracked through federal nutrition programs.
In a statement Monday, CDC researcher Cynthia Ogden noted that the CDC paper said the finding in young children "should be interpreted cautiously." She said CDC has data going back for several decades "but for the purpose of this paper we were only examining the last 10 years of data. And we're confident in our analysis for this time period."
It is possible some small decline in preschoolers is underway, says Thomas Robinson, a professor of pediatrics at Stanford University. "I think there's enough evidence to suspect we're probably seeing some bending of the curve, a little improvement," he says. "But there's certainly no reason to pat ourselves on the back." Robinson was not involved in either study.
The overall findings on children from the CDC study and the new study are the same: The total child obesity rate has stalled in recent years, holding at about 17% for nearly a decade. The adult obesity rate is about twice that and also holding steady, CDC says.
The most troublesome new finding, Skinner says, is that the share of children and teens who are extremely obese increased, from 3.8% to 5.9% between 1999 and 2012. Those with the most severe form of obesity — equal to an adult with a body mass index of 40 — increased from 0.9% to 2.1%.
For a 10-year-old boy who is 4½ feet tall, obesity would start at 95 pounds, severe obesity would start at 115 pounds and the most severe form would start at 130 pounds, the researchers say.
The heaviest kids "are the children we worry about the most," Skinner says. "You can't just tell that kid to eat more fruits and vegetables and everything will be better."
All obese children are at risk for obesity and health consequences as adults. Severely obese children are also at risk for immediate problems, such as high blood pressure, high blood sugar, abnormal cholesterol numbers and sleep apnea, experts say.
"These children are really on track to become the sickest adults," Robinson says.
Lee Michael Kaplan, a gastroenterologist who directs an obesity treatment program at Massachusetts General Hospital, says the trend toward higher weights among those who are obese has been seen in both children and adults in previous studies.
"I think it's real," he says. "People are getting heavier and heavier. The problem is not going away."