Worldwide, children are becoming heavier at younger and younger ages. In the United States, 19 percent of kids between the ages of 6 and 11 are overweight.
Being overweight or obese puts you at risk of heart disease, diabetes, cancer and other ills.
The first study looked at a group of almost 277,000 Danish children -- all schoolchildren in Copenhagen -- from 1930 to 1976.
Out of that initial group, more than 10,200 men and 4,300 women were identified whose childhood body-mass index (BMI) data were available and who had received a diagnosis of coronary heart disease (CHD) or died of CHD as adults.
Boys with a higher BMI at 7 to 13 years of age and girls with a higher BMI from 10 to 13 years of age had a higher risk of a heart disease event in adulthood, the researchers found.
The authors used as an example a 13-year-old boy who weighs 11.2 kilograms (24.6 pounds) more than average boy his age. He now has a 33 percent increase in the probability of having a coronary event before he turns 60, the Danish team said.
"It's scary," Kimball said. "We knew that if you're an overweight kid, you're at a higher risk to be an overweight adult. This study goes a step further. It's proving that you have an increased risk of cardiovascular events as early as 25 years of age."
The second study projected the number of overweight adults based on the number of overweight adolescents in 2000.
Using a computer model, it predicted that up to 37 percent of men and 44 percent of women will be obese when these people -- now teenagers -- turn 35 in 2020.
This could result in up to 5,000 additional deaths from heart disease and 45,000 heart attacks, cardiac arrests and related events by 2035 among this group of young adults. It would raise the death toll from obesity-related coronary heart disease by 19 percent.
"To some extent, we're not surprised. We know it's not good to be overweight at any age but we were really struck by the magnitude of this increase," said Bibbins-Domingo. "We're modeling a young adult population 35 to 50 years. These are people who should be working and raising families, not worrying about heart disease, and we're suggesting more will be hospitalized for heart attacks, will need chronic medication to manage high blood pressure and high cholesterol, and many more will actually die before the age of 50."
More information
To learn more about the government's We Can! Program regarding childhood obesity, visit the U.S. National Heart, Lung, and Blood Institute.
