Children and adolescents consume more calories and soda and have poorer nutrient-intake on days they eat at either fast-food or full-service restaurants, as compared to days they eat meals at -- or from -- home.

A new study, by researchers at the University of Illinois at Chicago and published online by Archives of Pediatrics & Adolescent Medicine, is the first to look separately at fast-food and full-service restaurants. The researchers examined calorie intake, diet quality, and consumption of sugar-sweetened beverages, particularly soda, on days when youngsters ate out as compared to days they did not. They used data from the three waves of the National Health and Nutrition Examination Survey for the years between 2003 and 2008, which included 4,717 children ages 2 to 11 and 4,699 adolescents ages 12 to 19.

At restaurants, the researchers found, youths consumed higher amounts of sugar, total fat, saturated fat and sodium.

Take-out fared better in one regard -- the researchers found adolescents consumed twice as much soda when eating in the restaurant, as compared to when they ate the restaurant food at home.

"We attribute that to the free refills," says Lisa Powell, professor of health policy and administration in the UIC School of Public Health and lead author of the study.

Children and adolescents also drank less milk on days when they ate at restaurants, she said.

In earlier studies Powell and colleagues found that 41 percent of adolescents consume fast food on a given day, in an amount that averages almost 1,000 calories. One-third of children ages 2 to 11 consume fast food on a given day.

The new study showed that on days when adolescents ate fast food, they consumed an additional 309 calories, suggesting they don't reduce their non-restaurant food intake enough to compensate. Young children took in an additional 126 calories. Full-service dining caused increases of about 267 calories for teens and 160 calories for children.

The concern, Powell said, is that kids are consuming fast food too frequently, and not in moderation.

Limiting consumption from restaurants would help "improve diet outcomes among children and youth," she said. Better nutritional standards are needed "to improve the range of healthy food options available, in order to turn around the obesity trend."

The researchers also found fast food had even greater adverse effects on diet for lower-income children, potentially increasing health disparities. Lower-income teens who consumed fast food took in more sugar, total fat, saturated fat, and sodium than their higher-income peers.

“When lower-income youths are eating fast food, they are choosing more energy-dense, lower quality foods that tend to be higher in fats and sodium and can be purchased cheaply,” said Powell, who conducts her research at UIC's Institute for Health Research and Policy.

"They are not going to the fast-food restaurant and getting a salad or the healthier turkey sub with lots of veggies."

Fast food is heavily promoted to children through television ads, the researchers say. Fast-food restaurants tend to cluster around schools and are more prevalent in low-income neighborhoods.

"We need an environment that promotes healthy rather than unhealthy food and beverage choices," Powell said.

Powell's co-author on the study is UIC graduate student Binh T. Nguyen. The study was supported in part by grants R01CA138456 from the National Cancer Institute and 111PA1102973 from the U.S. Centers for Disease Control and Prevention.

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