The finding isn't a prediction -- it's hard data from very long-term data on 10,235 men and 4,318 women born in Copenhagen, Denmark, from 1930 through 1976.
But given the size of the ongoing obesity epidemic, the findings predict a huge wave of future heart disease.
Researchers Jennifer L. Baker, PhD, and colleagues at Copenhagen's Center for Health and Society painstakingly compiled records for virtually every schoolchild in the city and matched them with national health records.
The bottom line: After the age of 7, overweight children have an increased risk of adult heart disease. The higher a child's body mass index -- BMI,which relates weight to height -- the higher that child's risk of becoming an adult with heart disease.
"What we found was at the age of 7, for both boys and girls, the risk was moderate," Baker tells WebMD. "By age 13, the risk increased dramatically."
A child does not have to be hugely obese to be at increased risk.
"We compared the average 13-year-old boy, who weighed 96 pounds, to a heavier boy of the same height who weighed 121 pounds," Baker says. "Even for a normal-weight boy, there is a one-in-nine risk of heart disease by age 60. For the heavier child, this risk becomes at least one in six. We find that highly significant."
Pediatric cardiologist Tom Kimball, MD, of Cincinnati Children's Hospital, says the findings are a warning that parents must take childhood weight problems seriously -- even in young children.
"This is not an adult problem. It is a kid problem," Kimball tells WebMD. "This study has a big message for parents."
During the 46 years of the study, an overweight child's risk of becoming an adult with a sick heart did not change much. The problem did not so much appear to be the modern diet as the simple fact of being overweight as a child.
Tsunami of Heart Disease Predicted
A computer simulation by Kirsten Bibbins-Domingo, PhD, and colleagues at the University of California, San Francisco, suggests that today's teen obesity epidemic means that by 2020, 30% to 37% of 35-year-old men and 34% to 44% of 35-year-old women will be obese.
By 2035, there would be up to a 16% increase in heart disease cases, with over 100,000 cases due to obesity, the researchers predict.
Both the Baker and Biggins-Domingo reports appear in the Dec. 6 issue of The New England Journal of Medicine.
In an editorial accompanying the studies, Harvard researcher David S. Ludwig, MD, PhD, predicts that by 2050, the U.S. obesity epidemic will cut Americans' life span by two to five years. That effect would be equal to the effect of all cancers combined.
"We lack anything resembling a comprehensive strategy for encouraging children to eat a healthful diet and engage in physical activity," Ludwig writes.
He suggests that a sensible strategy would:
- Regulate junk-food advertising
- Fund healthy lunches and physical activities at school
- Restructure farm subsidies to reward production of nutrient-dense produce rather than calorie-dense produce
- Require that insurers cover programs to prevent and treat child obesity
At the bottom of the Pandora's box of child obesity, Baker finds hope.
"Even though we are showing that children's body size puts them at risk, there is still a ray of hope in what we find," she says. "Because risks are moderate at age 7 and increase by age 13, it suggests that helping these children attain and maintain appropriate weight -- even during this short time -- can really improve their future outlook."