Overweight teens eat about 400 more calories on a day when they consume fast food compared with a day when they don't. But normal-weight adolescents eat virtually the same calories on either day, a study in today's Journal of the American Medical Association reports.
The researchers also found that teens generally consume about 1,600 calories worth of fries, chicken nuggets, cookies and soda during one fast-food meal. Kids that age need an average of about 2,600 calories a day.
The study adds to the growing body of research on the reasons for childhood obesity in the USA. About 75% of adolescents eat fast food at least once a week. And some experts have suggested that fast food plays a bigger role in weight gain for some children than others.
To examine this question, researchers at Children's Hospital in Boston recruited 54 participants, ages 13 to 17, who reported eating fast food at least once a week. About half were overweight, and the other half were normal weight. The teens were asked to recall their food intake for four days: two when they ate fast food and two when they didn't.
The findings: Overweight kids ate 2,703 calories on the days they ate fast food and 2,295 on the other days. Kids at a normal weight ate 2,575 calories on fast-food days and 2,622 on the other days.
However, the number of calories consumed by the heavy kids may actually be higher: Other studies have shown that overweight people tend to under-report calories.
In the second part of the study, the teens came to a food court, where they were offered an extra-large order of fries, chicken nuggets, chocolate chip cookies and a 20-ounce soda.
They were given refills when they had consumed three-quarters of their food. Empty soda containers were replaced with full ones. They were told to eat as much or as little as they wanted during the one-hour meal.
Researchers monitored the intake and found that, overall, teens ate an average of 1,652 calories at the fast-food meal or about 62% of their calories for the day. Overweight children ate 1,860 calories compared with 1,458 calories for the leaner kids.
''Adolescents tend to massively overconsume calories during a supersize fast-food meal,'' says pediatric endocrinologist David Ludwig, director of the obesity program at Children's Hospital.
On the days they eat fast food, overweight kids don't seem to compensate for the huge portion sizes; leaner kids do by eating less throughout the day, he says.
In other obesity news in the journal, a large government study indicates that the percentage of overweight and obese people in the USA didn't change significantly from 1999-2000 to 2001-2002.
In 2001-2002, 65.7% of adults were overweight or obese, compared with 64.5% in 1999-2000. About 16.5% of kids were classified as overweight in 2001-2002 compared with 15% in 1999-2000. The differences were not considered statistically significant.
''It's too soon to tell if the increase in the percentage of overweight or obese people that we've seen over the past two decades is stopping or continuing,'' says lead author Allison Hedley, an epidemiologist with the Centers for Disease Control and Prevention.
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