"While too much of both types of screen time encourages sedentary behavior, our study suggests high TV time in particular is associated with poorer food choices and increased cardiovascular risk," said Elizabeth Jackson, M.D., M.P.H., associate professor, Division of Cardiovascular Medicine, University of Michigan Systems, Ann Arbor, Mich., and the senior author of the study.
In fact, sixth-graders who reported watching between two and six hours of TV a day were more likely to have higher body mass index, elevated systolic and diastolic blood pressure and slower recovery heart rate compared with those reporting low screen time or kids who had comparable computer/video game use. This is the first time researchers have looked at the impact of different kinds of screen time kids get in relation to snacking habits and physiological measures associated with heart health, according to the authors.
The study included 1,003 sixth-graders from 24 middle schools participating in Project Healthy Schools across five diverse communities in Southeast Michigan. Researchers used standardized questionnaires to collect information about health behaviors including the type and frequency of screen time, snacking habits, and food and beverage choices in the last 24 hours. Physiological measurements were also assessed, including blood pressure, cholesterol, heart rate recovery after exercise (a marker of fitness), height and weight. Students were divided into three groups: low screen time (less than one-half hour a day), high TV time (two to six hours a day) and high computer/video games (two to six hours a day). Self-reported snack behavior and physiologic markers were then compared.
The research found that kids who spent more time in front of a screen - regardless of the type - snack more frequently and are more likely to choose less healthy snacks. High TV viewers and computer/video game users both reported eating roughly 3.5 snacks a day - one full snack more than kids who had minimal exposure to these technologies. But children who watched two to six hours a day of TV were more likely than the high computer/video game group to eat high-fat foods such as French fries and chips.
Jackson said this is likely because these kids are bombarded by TV commercials that tend to reinforce less healthy foods - often higher in sugar, salt and fats. In addition, kids tend to have free hands while watching TV as opposed to when they are on the computer or playing video games, which provides more opportunity for mindless snacking. Earlier studies have also shown that children tend to eat more when they watch TV.
"Snacks are important, and choosing a piece of fruit rather than a bag of chips can make a really big difference for one's health," Jackson said. "Parents need to monitor their kids' activities. Our results offer even more reason to limit the amount of TV time kids have and are right in line with current recommendations."
The American Academy of Pediatrics recommends limiting entertainment screen time to less than one or two hours per day. But children actually spend a whopping seven plus hours on entertainment media each day - 4.5 of which are spent watching TV. Excessive media use has also been linked to obesity, attention problems, school difficulties and sleep and eating disorders.
"The wealth of studies now show a significant link between being overweight in childhood and continuing that trend into adulthood," Jackson said. "The more we can change behavior early on to promote healthy weight and dietary habits, the more likely we will be able to reduce adult-related problems including heart disease, diabetes and high blood pressure."
Researchers did not collect information about whether kids actually snacked while watching TV; nor did this study include newer generations of video game platforms such as Wii that promote some activity. Compared to kids reporting low screen time, the high computer/video game cohort was not associated with elevated blood pressure or body mass index; however, these numbers might be expected to change over time with prolonged sedentary behavior and should be further investigated. Jackson said future studies are also needed to examine interventions that can reduce unhealthy snacking and television watching, while also promoting healthy activities and foods.