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Teens most guilty of underestimating calories in fast food, study reveals

Fast-food items may have way more calories than some of us -- especially teens -- think, according to new research.

"We found that people, especially teens, are consuming more calories than they think they're getting when they eat fast food," lead researcher Dr. Jason Block, of the Harvard Medical School/Harvard Pilgrim Health Care Institute, said in a press release.

The study, which was published in BMJ on May 23 and funded by the Robert Wood Johnson Foundation, showed that teens underestimate the number of calories in their meals by as much as 34 percent. But they're not alone: Parents of school-age children underestimated fast food meal calories by about 23 percent, and adults by as much as 20 percent, Block pointed out.

In total, 1,877 adults, 1,178 adolescents (aged 11 through 20) and 330 school-aged children (3 to 15) were surveyed at 89 fast-food restaurants in four cities in the New England area. A quarter of the study participants underestimated their meals caloric value by at least 500 calories.

Adults on average ordered an 836-calorie meal, but they thought what they were eating contained 175 fewer calories. Teens bought about 756 calories per meal, but they underestimated by 259 calories on average. Children had meals that were 733 calories on average, but underestimated by 175 calories.

Different food chains also brought different results. People who ate at Subway were more likely to underestimate their calories than those who ate at McDonald's, Burger King, KFC, Wendy's, and Dunkin' Donuts. Subway adult and teen customers were 20 and 25 percent less accurate respectively than those who ate at McDonalds. Block feels that this may be due to a "health halo" provided by Subway's marketing.

"These findings tell us that many people who eat at fast-food restaurants may not be making informed choices because they don't know how many calories they're consuming," said Block. "Having the information is an important first step for anyone wanting to make changes.

Another study, published online May 23 in the American Journal of Public Health, showed that kids who eat fast food at least twice a week were 50 percent less likely to use caloric and nutritional information than children who ate at these establishments less frequently.

Researchers surveyed 721 American youth between 9 and 18 about their eating habits, and asked them for their age, gender, height, weight and how often they ate fast food. Kids who never ate fast food (about 8 percent of the group) and kids who didn't realize there was caloric information available (about 20 percent) were excluded.

Overall, 42.4 percent of the group said they used the nutritional guides if they were available, but those who ate at fast food restaurants at least twice a week were 50 percent less likely to use the information than those who ate the food less frequently.

Girls were 80 percent more likely to use the calorie information than boys, and obese kids were 70 percent more likely to report using the guides than normal weight youth.

"Our findings are important given the high prevalence of obesity among youth and the adverse health effects associated with obesity. It is encouraging that a large number of youth, particularly youth who are obese, reported using the calorie information. This may have potential to lead to improved food and beverage choices as a way to manage weight, although more research is needed to assess whether youth know how many calories they should consume in a day given their activity level," lead author Dr. Holly Wethington, a researcher with the Centers for Disease Control and Prevention's Division of Nutrition, Physical Activity, and Obesity, said in a press release.

"Public health practitioners, school nutrition services, retailers, and other interested groups can consider implementing complementary education programs to improve youth's understanding of calorie information to hopefully make calorie labeling part of a successful weight management strategy."

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