July 25, 2011 -- U.S. children are eating more, and the extra calories often come from foods eaten while they are away from home, according to a new study.
Overall, children eat about 179 more calories a day than children did three decades ago, says study researcher Jennifer M. Poti, a doctoral student at the University of North Carolina, Chapel Hill.
"We found kids eat a relatively constant level of calories at home," says "But in addition to that, kids are eating an increasing number of calories outside the home."
Fast food, including food taken home to eat, and store-bought prepared foods are also fueling the rise in calories, she says.
The findings may help parents help their children to reduce excess calories, she says. Childhood obesity has more than tripled in the last 30 years, according to the CDC. About 18% of U.S. children 12 to 19 are obese.
The study is published in the Journal of the American Dietetic Association.
Where the Calories Come From
Poti evaluated data from four national food surveys. The data included more than 29,000 children ages 2 to 18 years old. The earliest data were from 1977 and the latest from 2006.
"No previous studies have examined where the food is eaten," Pot says. "This study looked at where they got it and where they ate it."
The average daily increase of 179 calories, from 1977 to 2006, was even higher in the preschoolers, ages 2 to 6. Their calories rose by 241 a day.
When the researchers looked at where the food originated, they found the percent of calories eaten away from home rose from 23.4% in 1977 to 33.9% in 2006.
The largest source of calories from foods eaten away from home was from store-bought prepared foods, Poti says. The percent of calories eaten from fast food was more than that from food eaten at school.
Overall, calories from foods eaten away from home increased by 255 calories a day.
Fast foods and store-bought prepared foods are often of poorer nutritional quality than home-cooked foods, Poti tells WebMD.
Parents should be aware that where food comes from is important, she says. "Eating outside the home does tend to increase the number of calories kids eat during the day."
To compensate, parents can limit the amount of food eaten away from home or fix less food at home on a day when children have eaten a lot away from home, she says.
Convenience Part of the Blame?
''This should be a bit of a wake-up call of where excess calories that have led to increasing rates of obesity are actually coming from," says Lona Sandon, RD, assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center, Dallas. She reviewed the findings for WebMD.
"School lunch has taken much of the rap and blame for childhood obesity," she says. "Yet this study turns the table on that and suggests that fast food and ready-to-eat foods from stores that replace home-cooked food may actually be the bigger culprit."
Families need help in how to make healthier choices when buying food prepared outside the home, she says.
The study suggests that ''convenience is a major driver of food selection for families in this fast-paced world of ours," says David Katz, MD, MPH, director of the Yale University Prevention Research Center and editor-in-chief of the journal Childhood Obesity.
The findings also suggest that improvements in school nutrition, while important, aren't enough to solve the childhood obesity epidemic, he says.