Entertaining TV Affects BMI Levels In America's Youth
April 8, 2013

Entertaining TV Affects BMI Levels In America’s Youth

Lawrence LeBlond for redOrbit.com - Your Universe Online

A lot of research has focused on how TV affects today´s youth. One recent study has suggested that what´s on TV makes children antisocial, while another claimed there was no link between a child´s negative social development and sitting in front of the tube for too long.

When it comes to obesity, previous research has also suggested that TV in the bedroom may be a factor in ballooning waistlines of young children. A 2009 study had also found that not just TV shows, but the commercials in between those shows, were adding to the obesity epidemic in children.

Following on all the latest research surrounding television influences on children, findings from a new study by researchers at Harvard University indicate that children who are engrossed in what´s on TV are experiencing higher body mass index (BMI) ratings than those who do not find TV that entertaining.

Compared with teenagers who didn´t pay much attention to what was on TV, teens who gave it the highest level of attention had an estimated 2.4-point higher BMI rating, according to David Bickham, PhD, of Harvard, and colleagues.

The researchers, however, found no association between other forms of screen media and an increased BMI rating. This included playing video games, surfing the net and using mobile devices. The research team also found no significant association between hours of time spent engaging with screen media and BMI. A paper on their findings is published in the current issue of Pediatrics.

The association between screen media and BMI rating may stem from advertising of unhealthy food and drink through TV, assert the Harvard team.

Unlike other forms of screen media, ads are commonplace on TV, with a bulk of commercials focusing on children and teens during peak viewing hours and across stations geared toward adolescents, such as Nickelodeon and Cartoon Network.

"Despite dramatic shifts in how young people use media, TV, the only screen medium that consistently delivers food advertising, remains the most used," the researchers wrote.

Bickham and his colleagues added that they did not test for specific mechanisms of action, but noted that their findings of “the importance of attention to TV is consistent with advertising effects.”

"For advertisements of energy-dense, nutritionally questionable foods to affect preferences, the viewer must receive the message by paying attention to a medium that delivers this content," Bickham's group explained, as cited by MedPageToday.


For the study, Bickham and colleagues developed a data collection methodology for various forms of screen media use by relying on recall estimates, time-use diaries, and ecological momentary assessment (EMA). The team recruited 91 young adolescents, ages 13 to 15, from a small New England city for the research.

The participants were randomly assigned to complete a week-long self-assessment of media and 24-hour time use diaries on a random weekday and a Saturday. For validation purposes, the subjects were required to redo the task for another week and day.

The team measured attentiveness through a questionnaire that asked the participants to report what they were paying attention to most. Responses included, people, reading and/or doing homework, sports or activities, screen media, or something else. When media was selected, the questionnaire included subcategory responses such as computer, video games, phone, music, or TV.

More than half of the participants in the study were white (62.6 percent), but the group was equally divided by sex (45 girls and 46 boys). The median age of participants was 14.

During the EMA signaling part of the study, the researchers determined that time spent watching TV was 402.9 minutes over 48 hours. Video game and computer time over the same 48 hours was 95.1 minutes and 140 minutes, respectively. Primary attention was mostly focused on TV, compared to all other forms of screen media.

The researchers found that duration of media did not significantly affect BMI, regardless of the type of media used. They did, however, find that duration of physical activity had a significant negative impact on BMI rating.

The authors noted that the higher BMI rating could be a result of “℠unconscious eating´ while distracted by TV from physiological hunger and satiety signals,” noting that children typically consume energy-dense snacks while watching TV and are less aware of the amount of those snack foods they are eating.

Bickham and colleagues said the study was limited by cross-sectional data that cannot define the direction of effect to observed associations.

However, the results are significant, adding to the concern that America´s youth are quickly becoming obese. On a national scale, a third of adolescents between 2 and 19 years of age are obese or overweight, according to government statistics.


Also in Pediatrics this week, another small study that focused on 41 first-graders found that when given large, adult-sized dinner plates, students served themselves larger portions of food and consumed nearly 50 percent of the extra calories on their plate.

That study, conducted by researchers at Temple University in Philadelphia, found that on average, 80 percent of kids served themselves 90 extra calories at lunch time when using the adult dinner plate than children did who used a normal child-sized plate (about the size of an adult salad plate). And when children said they liked the meal, they served themselves and additional 104.2 calories, on average.

"We know large portions have a pretty consistent effect in making kids eat more than they would if the portion sizes were smaller," said study co-author Jennifer Orlet Fisher, an associate professor of public health at Temple. "It really seems that offering kids smaller plates could actually be potentially helpful in keeping portion size in check and maybe appetite in check."

Another study this week in Pediatrics found that sleep also plays a significant role in BMI levels in children.

A new sleep study provides strong evidence that insufficient sleep may contribute to the rise in adolescent obesity. Sleep deprivation increasing BMI levels is based on the finding that it increases levels of a hunger hormone and decreases levels of a fullness hormone, which could lead to overeating and obesity.

Study author Jonathan Mitchell, a postdoctoral fellow in biostatistics and epidemiology at the University of Pennsylvania in Philadelphia, used data collected every six months over a four year period from nearly 1,400 high school students.

Results of that study indicate that increasing sleep from 7.5 hours per night to a medically recommended 10 hours per night could reduce a teen´s BMI by 3 percent at age 14 and by 4-6 percent by age 18.

"It's a prediction, not conclusive data, but the findings point to the potential public health benefits that increasing sleep duration could have for overweight and obese adolescents in the U.S.," said Mitchell, as cited by USA Today.