The association between television viewing and childhood obesity is directly related to children's exposure to commercials that advertise unhealthy foods, according to a new UCLA School of Public Health study published in the American Journal of Public Health.
The study, conducted by Frederick J. Zimmerman and Janice F. Bell, is the first to break down the types of television children watch to better determine whether different kinds of content may exert different effects on obesity.
The researchers gathered data from primary caregivers of 3,563 children, ranging from infants to 12-year-olds, in 1997. Through time-use diaries, study respondents reported their children's activities, including television viewing, throughout the course of an entire weekday and an entire weekend day.
Caregivers were also asked to report the format- television programs, DVDs or videos- and the names of the programs watched. This data was used to classify television viewing into either educational or entertainment programming and to determine whether or not it contained advertising or product placement. A follow-up was conducted in 2002.
The analysis controlled for the amount of physical activity and the children's gender, age, race/ethnicity, mother's body mass index (BMI), education and sleep time.
Among all children, commercial viewing was significantly associated with higher BMI, although the effect was stronger for children younger than 7 than for those older than 7, the study found.
"The persistence of these results, even when the child's baseline weight status was controlled, suggests that the association between commercial television viewing and obesity does not arise solely or even primarily because heavier children prefer commercial television," said Zimmerman, professor and chair of health services at the School of Public Health and the lead author of the study.
Non-commercial viewing, including watching DVDs or
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University of California - Los Angeles