Ask Dr. Hallberg: Is watching TV unhealthy?

TV may be killing you. It's not some righteous bumper sticker. It's backed up by research. Americans spend an average of five hours in front of the TV, by some estimates. Now a new study shows that two hours a day can have a negative impact on your health.

Researchers at the Harvard School of Public Health found a higher risk of diabetes, heart disease and even death among TV watchers. Each two hours of TV a day increased the risk of dying by 13 percent.

MPR's regular medical analyst Dr. Jon Hallberg joined All Things Considered host Tom Crann to talk about the study.

Tom Crann: Headlines like "TV causes death" get your attention, but what really did this study find?

Dr. Jon Hallberg: It's not even really a study in the sense of a research study. It was a meta-analysis. The researchers asked the question: Can we show there's a link between TV watching and bad health. There aren't a lot of studies out there that really get at this. They went back to 1970 and '74, all the way up to 2011 — they really cast their net widely. There were 1,600 studies that looked at some aspect of this, but they only found eight that could really be used for analysis for this. What they found is not a lot of new information.

Crann: Does this data show causality with watching TV or just a lack of exercise?

Hallberg: That's it. There's an association they found. An association is fairly weak, it's not an actual causal relationship, but they concluded that it's biologically plausible that watching television can lead to these problems. If you're watching TV for hours at a time, and the average American is doing this five hours a day, there's something else you're not doing: You're not being active, you're sitting there. And that's ultimately not very healthy. When people are watching TV for that much, they're also eating. Typically you're not eating fruits and vegetables while you're watching television. You're having your meals there, you're eating things that are being advertised on TV. It's high calories and little activity and that's a bad recipe for health.

Crann: That leads to what? Heart disease, what else?

Hallberg: Heart disease and diabetes. Sedentary lifestyle, putting on weight, eating too much, those are the big risks for diabetes and heart disease.

Crann: Why are studies like this so important?

Hallberg: In the article they get at the fact that outside of our jobs and sleeping, we spend more time watching TV than any other single activity in the industrialized world. In the U.S. it's 5 hours, in Europe and Australia it's somewhere between 2.5 to 3 hours. So it's a problem all over the developed world. TV is incredibly passive. Watching something requires almost no metabolic output and doesn't require much in the way of thinking either. So you can see if you're a public health person, there's really some interest here in terms of a public health policy and overall health.

Crann: Why do they do studies like this when the results seem so intuitive?

Hallberg: I ran this by a colleague too, and we both agreed that this is one of those "duh" studies. Of course if you just sit and do nothing it's not going to be very healthy. But it's one thing to think that and another thing to prove it and back it up with some numbers. I think this is an attempt at that. What we don't know from this study is if you turn off the TV, does that actually lead to better health.

Crann: Are doctors going to start asking us how much TV we watch?

Hallberg: We already do. Add one more thing to the checklist of things we're supposed to ask. With kids especially, the American Academy of Pediatrics already puts this as one of the first questions we ask kids. But we're changing the word from television to screen time — video games, computers. I think it's worth bringing up. Most parents are readily willing to talk about it because they realize kids shouldn't plant themselves in front of a screen for hours and hours on end.

(Interview transcribed by MPR reporter Elizabeth Dunbar.)

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