NEW YORK - Watching high-energy TV programs might make watching calories harder, a new study suggests.
With snacks freely available, young adults watching an action movie ate almost twice as much food as those watching an interview show, the researchers found.
Those watching the action movie ate more even if the sound was turned off.
"What we found was that even watching the silent film generated a large increase in what people ate compared to the talk show," said coauthor Aner Tal at Cornell University in Ithaca, New York.
He and his colleagues divided 94 college students into three TV-watching groups. One group watched 20 minutes of the 2005 science fiction action thriller The Island, directed by Michael Bay, another watched 20 minutes of the PBS interview programme Charlie Rose, and the third watched The Island with the sound off.
As Tal and his colleagues note in their research letter in JAMA Internal Medicine September 1, The Island averages more than 24 camera cuts per minute and Charlie Rose has only 4.8 cuts per minute.
The students each had access to bowls of M&Ms, carrots, cookies and grapes and could eat as much as they wanted.
Students watching The Island with sound ate 207 grams of food on average, compared to 104 grams for those watching Charlie Rose. Over the 20-minute period, action movie watchers consumed 354 calories, 104 calories more than talk show watchers.
Even without sound, students watching The Island ate 40 more grams and 100 more calories than those watching Charlie Rose.
Quite a lot of research has found that TV viewing is associated with increased food intake and especially snack consumption, said Dr. Jean-Michel Oppert of the University Pierre et Marie Curie in Paris. What is new is the focus on specific TV content, he said.
Oppert was not an author on the new research paper.
"There is no information in the paper on when during the day the experiment was performed," Oppert told Reuters Health by email. "It may have some importance to provide snacks before or after a meal, or at different times during the day."
Tal and his coauthors attribute the increase in snacking to the more distracting nature of the action movie, with more camera cuts and higher sound source fluctuation.
When you're more distracted by what you're watching, you pay less attention to internal cues about how you actually feel and may keep eating after you are full, Tal told Reuters Health by phone.
"In this case we looked at variations in one thing that distinguishes action movies, which is how dynamic they are, how many cuts per minute, and variation in sound as well," but that may not explain the whole situation, he said.
Watching sports may have the same effect on snacking as an exciting movie, he said.
It seems especially important that more distracting TV led to more snacking even without sound, Tal said.
"There are a lot of locations where people might get exposed to TV where there is not sound, like the TVs in restaurants or bars," he said. "Those settings can influence what people eat."
Bars in particular tend to have bowls of snacks available, and those are continually refilled, he noted.
"In general it might be a good idea not to have endless bowls of fatty stuff in front of the TV regardless of the content," Tal said.
If you're going to snack while channel-surfing, choose healthy snacks and have them portioned out in advance, he suggested.
"Use a proportioned bowl and then you know that's what you'll be eating," he said. "Mindless eating tends to happen when the food is easy to get. When you need to get up and get to the kitchen, that could deter you."