Heavy Player One: How Screen Time and Snacking Impacts Adolescent Obesity

A study presented at ENDO 2019 seems to indicate a link between teens who spend a lot of time in front of a screen and poor metabolic health. Due to the propensity of so many adolescents to snack while they gaze at everything from a television to a cell phone, strategies are needed to address these unhealthy habits.

Here in 2019 we live surrounded by screens: televisions, computers, tablets, phones, and on and on. This is not always necessarily a problem; people use computers for work or they read novels on their tablets or video chat with loved ones around the world.

But as we’ve entered this brave new world, studies have linked excessive screen time to the growing epidemic of childhood obesity and increased risk for adolescents developing metabolic syndrome, which in turn could lead to a higher risk for developing subclinical atherosclerosis and type 2 diabetes as an adult. Metabolic syndrome affects near 25% of the adult population and approximately 5.4% of children and adolescents in the U.S.

But according to research presented at ENDO 2019 in New Orleans, these studies have had inconsistent results due to methodological differences among them. “The main question has emerged from literature and the interest of some students in my lab about lifestyle and cardiometabolic health among adolescents,” says lead researcher Beatriz Schaan, PhD, of the Universidade Federal do Rio Grande do Sul in Porto Alegre, Brazil. “Screen time has been studied as a potential new risk factor for cardiometabolic health. However, it seems not to be totally independent from other behavioral risk factors, such as unhealthy eating habits.”

Unhealthy Patterns

Schaan and her team set out to investigate the association between screen-based sedentary times and metabolic syndrome, and whether this association is modified by children and adolescents consuming unhealthy snacks. The research was part of the Study on Cardiovascular Risks in Adolescents (ERICA), a nationwide school-based survey of Brazilian teens. The study included data on 33,900 teens ages 12 to 17 years.

“Screen time has been studied as a potential new risk factor for cardiometabolic health. However, it seems not to be totally independent from other behavioral risk factors, such as unhealthy eating habits.” –  Beatriz Schaan, PhD, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

Schaan says that they first investigated whether the link between screen time and metabolic syndrome was independent of physical activity and total energy intake. “At this point, we observed that including these variables in the analysis reduced the strength of the association between screen time and metabolic syndrome, but did not eliminate it,” she says.

Next, the researchers turned their focus to eating behaviors – specifically unhealthy snacking patterns – and found an interaction between screen time and unhealthy snack consumption while in front of screens. “This analysis partially changed our interpretation about the results, showing to us that unhealthy snack intake in fact plays a very important role in the association between screen time and metabolic syndrome among adolescents,” Schaan says.

The researchers measured the teens’ waists and blood pressure, and took blood samples to measure blood glucose, HDL-cholesterol, and triglycerides. Screen time was self-reported and categorized as two or fewer hours a day, three to five hours a day, and more than six hours a day. Snack intake was also self-reported, with answers separated as no (no habit of snacking while in front of a screen) or yes (snacking sometimes or every day). Almost 60% of the teens were female, and the average age was 14.6. About half of the teens were physically active; 85% said they usually eat snacks in front of the TV, while 64% usually ate snacks while using the computer or playing video games.

The researchers found 2.5% of the teens had metabolic syndrome. Those who spent six or more hours a day in front of screens were 71% more likely to have metabolic syndrome compared with those who spent less time in front of screens. However, heightened risk was only seen in those who reported usually eating snacks in front of screens. There was no association between screen time and metabolic syndrome among teens who reported no snacking in front of screens. Among teens who reported habitually eating snacks in front of the TV or computer, the risk for metabolic syndrome rose the longer teens spent in front of screens.

“When we observed that total energy intake materially unchanged the association between screen time and metabolic syndrome and decided to explore unhealthy eating behaviors, we thought that the low nutritional quality of the snacks combined with the entertainment in front of screens, which may induce an unhealthy food intake, could be the key for this conundrum,” Schaan says. “Thereafter, the results confirmed that hypothesis, at least in part.”

Screens, Screens Everywhere

Of course, many health organizations recommend limiting screen time each day, and while that certainly seems like a simple suggestion, it’s not always an easy one to follow given the sheer ubiquity of screens – especially in young people’s lives. “Indeed, today young people live surrounded by screens and it’s not always a bad thing,” Schaan says. “Thus, limiting the consumption of junky food in front of screens can be easier than avoiding screen-based activities.”

“High screen time and unhealthy snacking are harmful to adult health too; however, it’s difficult to say if our results would be similar if we replicate these analyses in adults. Adult behavior can be easily adopted by youth, so if adults limit their screen time and avoid unhealthy snacking, they will collaborate to make a healthier environment at home.” – Beatriz Schaan, PhD, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

Schaan says that she and her team believe that the relationship among screen time and unhealthy snacking and cardiometabolic health in adolescents can be considered synergic or at least complementary. “It is possible that unhealthy snacking occurring in front of a screen is the direct result of more exposure to the screens,” she says. “A circular pattern could also be occurring; for example, those who tend to eat unhealthy snacks while in front of a screen also tend to spend more time in front of screens, and this in turn leads to even more eating unhealthy snacks. However, this picture is not completely clear yet and more studies are needed.”

Strategies to address metabolic syndrome among adolescents should aim at limiting unhealthy snacking while in front of screens, Schaan says, which may reduce the strength of the association between total screen time and metabolic syndrome. Moreover, programs to reduce screen time and to adopt policies to incentivize a healthy diet through the media – such as restricting junk-food advertisements during children’s shows — can be helpful to improve metabolic health in this population.

For now, Schaan says that the adolescents involved in the study and their parents were very interested in the results, since they could make some relatively simple lifestyle changes that could possibly lower their future cardiovascular risk. “High screen time and unhealthy snacking are harmful to adult health too; however, it’s difficult to say if our results would be similar if we replicate these analyses in adults,” Schaan says. “Adult behavior can be easily adopted by youth, so if adults limit their screen time and avoid unhealthy snacking, they will collaborate to make a healthier environment at home.”

— Bagley is the senior editor of Endocrine News. He wrote about testosterone treatments in hypogonadal men with obesity in the June issue.

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