Researchers have found boys will eat a lot when placed in front of a television, computer or video game, and snacks are made readily available.
The researchers from the University of Auckland's National Institute for Health Innovation tested the snacking habits of 20 normal-weight boys aged 9-13 from the greater Auckland area.
Each boy spent three one-hour sessions in a study room, watching television, using a computer or playing video games.
Food and drink was placed on a nearby table, with the boys having to move if they wanted to get to it.
High-energy-density food and drinks provided included salami sticks, cheese and crackers, chocolate chip cookies, potato chips and Coca Cola, while low-energy-density foods and drink included apples, chocolate-flavoured yoghurt, carrot sticks and water.
A report of the study, published in Appetite, said total energy intake was significantly greater when the boys were watching television, than when they were using a computer.
There was also a trend toward greater energy intake when watching television than when playing video games.
Regardless of the variation, all three activities were associated with substantial energy intake during the one-hour exposure periods, the report said.
The researchers suggested the solution might not be to reduce the time involved in the activities, "given that these behaviours are highly rewarding and play such an important part in the lives of today's youth".
They said targeting screen-based sedentary activities might work better if they focused not on limiting sedentary time activity, but targeting the associated behaviours such as over-consumption of energy-dense food and drink.
The study found similar amounts of high-energy-density food was eaten during each of the three activities.
Consumption of low-energy-density food was greatest when the boys were watching television and lowest when using the computer. The boys also drank significantly more high-energy-density drink when watching television than when using the computer.
The researchers acknowledged the setting for the study did not accurately represent a home environment.
In a real-world setting, boys would not necessarily have open access to a wide range of highly palatable, energy dense food and drink. The study also did not account for the presence of other people such as friends, siblings and parents.
It was suggested television-watching might have increased energy intake, compared to computer use and, to a lesser extent, playing video games, due to something called "narrative transportation".
That referred to the feeling of being immersed in a story, and had been shown to significantly increase calorie intake, and to be greater while watching television compared to playing video games, the researchers said.
The differences in the intake of energy-dense foods could also have something to do with "associative learning".
While watching television during meals was a common activity in adolescents, pairing of food with video games and computers might be less common, the study said.
Both video games and computers required participants to use their hands, and there could also be more rules within a home about eating while involved in those activities.
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