Can Bruce Willis make you gain weight?

Obesity is a growing problem across the world, but some of our eating habits could be influenced by the type of TV we are watching. Aner Tal, from Cornell University in the US, looked at how much food volunteers ate while watching either an action-packed movie or a sedate talk show. He explained to Chris Smith how our watching and eating habits are closely linked... 

Aner -   Being distracted by watching TV can lead people to eat more.  What we wanted to find out is, if different TV content can lead people to eat more or less, depending specifically on how dynamic the content was or how engaged they are with the content.

Chris -   So literally, TV consumption can affect food consumption.

Aner -   Yeah.

Chris -   In what way?

Aner -   Basically, your attention is limited.  So, the more you're paying attention to what you're watching on the TV, the less you're paying attention to what you're eating.  So, if you're watching something that's very absorbing, you can just go on eating without realising it.

Chris -   So, how did you do the study?

Aner -   We randomly divided participants into three groups and each group watched 20 minutes of programming.  One group was given a segment of the action movie "The Island."  Another group was given a segment of the talk show, the "Charlie Rose Show" which is a fairly laid back, relaxed conversation type of talk show.  The third group was given the same segment from "The Island" but without sound.  Each person watching the shows was given an amount of snacks they had in front of them and they could eat while they're watching the shows.  And when they were done watching the show was, we measured how much they had eaten.

Chris -   What came out of it?  What did you find?

Aner -   People watching the action movie ate more snacks than people who were watching the talk show.  Even people who watch the action movie without sounds still ate considerably more than people watching the talk show.  So, they are 46% more calories, even watching the action movie without sound.  With sound, they ate 65% more calories.

Chris -   How many calories did they burn because it was exciting?

Aner -   I don't think it works that way?  I wish we could just watch like exciting TV or a sports TV and that would be our exercise.

Chris -   Was it genuinely that there's something about the content or the way that the programming works that makes people compulsively eat?

Aner -   I think so.  So, we're still doing some follow up investigations to get a more precise idea of what the process is, but you can, to some extent, have divided attention or shift your attention.  But if you're completely absorbed in something, then it'll be much more difficult to pay attention to something else.  So, if you're watching TV, you're not watching what you eat.

Chris -   And does this in some way subvert your brain's circuitry which logs how many calories are going in and tells you to stop eating?

Aner -   I would say, more than that, it's your paying attention to how you're feeling.  So, kind of getting that feeling that you know, "I've had so much chips, I already kind of feel like throwing up, so maybe I should stop."  If you're not paying attention to how you're feeling, you can just continue eating on automatic.

Chris -   Is there a relationship between sex - I don't mean the physical act of sex.  I mean, gender and this effect.  Do you see that men or women are more susceptible?

Aner -   Yeah, so I mean, there's probably a relation between the physical act of sex as well but...

Chris -   The reason I asked this is because obviously, we know that men find certain types of action movie more compelling than women.  If I turn on a thriller, my wife will often fall asleep whereas I'll still be watching it at midnight.  So, is there a sex susceptibility in this effect, do you think?

Aner -   We do think so and that's one of the initial pieces of evidence we got from this study that gives us a hint about what's going on because there was a bit higher consumption for males watching the action film than for females.  So, it had more of an effect of them and that might be because it engaged their attention more.

Chris -   So, what would your recommendations be to people who are traipsing off to the cinema or to their home cinema, armed with a box of popcorn?

Aner -   Leave the box of popcorn at home.  No, I think it's partly about controlling how you'll act when you're unconscious.  So, just assume you're going to go into a movie coma, you're going into something that you're going to be swallowed up in and either get a healthy snack.  That way, you'll be eating baby carrots versus chips or chicken wings.  Or just restrict the quantity you have.  So, just have a pre-determined amount and then you know that's what you're going to eat because that's what you have.  Even you can have a situation where you have more if you want to, but you'll need to actually go for the effort of getting up walking all the way to the kitchen which will also burn a lot of calories and getting more.  And setting things up that way versus just having a huge amount in front of you is going to prevent some of this mindless eating trap.

Chris -   So basically, make the fridge really hard to open so you'll at least burn some calories retrieving the supplementary salts.

Aner -  Yeah, you'll do aerobic activity walking to the fridge and then you'll build your muscles opening it.  Yeah, that's a good idea.