Overweight children who shed their excess pounds in adulthood don't face a higher risk of obesity-related health problems, an analysis of four studies involving children and adults in the United States, Australia and Finland has concluded.
The findings don't prove weight loss in itself will eliminate the extra risks, but they mean overweight or obese children are not automatically destined for higher rates of diabetes, high blood pressure and heart disease.
"There is hope for overweight and obese children," chief author Dr. Markus Juonala at the University of Turku told Reuters Health in a telephone interview. "If they manage to become non-obese adults, then the risks of these outcomes -- diabetes, hypertension, early atherosclerosis -- are quite similar to those who have been normal weight all their lives. I think that's quite a positive message."
In the United States, about one out of every six children and adolescents is considered obese.
The report in the New England Journal of Medicine combined data from four studies that followed more than 6,000 children for an average of 23 years.
"It's been thought that if you're an obese kid, it's all done," said Juonala. "But based on these findings what really matters is what you are at as adult."
The researchers just observed what happened over time and did not test whether actively bringing down a child's weight can stave off health problems later on. But the results suggest that "there's time and opportunity for intervention to help those children who are overweight and obese," Juonala said.
At the start of the studies, 12 percent of the children were overweight or obese, and two percent were obese. By adulthood, those figures had leapt to 55 percent and 21 percent, respectively.
The analysis also confirmed what doctors have known for years: being an overweight adult increases your risk of various health problems.
Compared to people who were normal-weight both as children and adults, obese adults who had been heavy as kids as well tended to face the highest risks.
About seven percent of them had type 2 diabetes, 29 percent had high blood pressure and 18 percent had high levels of "bad" cholesterol, for instance.
Among people who had never been overweight, only one percent had diabetes, 11 percent had high blood pressure and nine percent had high-risk levels of bad, or LDL, cholesterol.
All of these problems raise the chances that people will end up with heart disease, the leading killer worldwide.
For adults who had trimmed their waistline back from large to normal, however, the picture looked less bleak: Their rates of heart disease risk factors were no different from those of people who had been slim all their lives.
"Primary care physicians should not take the pessimistic view that once childhood obesity is established, cardiovascular risk is also determined," the researchers said.
Because previous studies have shown that getting children to lose weight reduces heart disease risk factors, the results appear solid, Dr. Albert Rocchini of the University of Michigan said in an editorial.
"If we want to reduce the incidence of adult heart disease and thereby start to control the continuing escalation in U.S. health care expenditures," he said, "now is the time to do whatever it takes to develop more effective methods for both the prevention and the treatment of childhood obesity."