We’ve all heard how to be fit, happy and healthy: eat better, exercise more and of course, watch less television. Watching TV has been vilified right alongside snacking on sugary, fatty foods and smoking as one of the most unhealthy things we can do, especially as a kid. But does TV deserve the bad rap? After about 50 years of study, the answer seems to be…well, sort of.

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The vast majority of health risks associated with TV-watching aren’t from the content itself, but from how we watch it—that is, sitting. The amount of TV a person watches is often used by scientists as a measure of how sedentary their lifestyle is. It’s the inactivity—not “Keeping Up With the Kardashians”—that really is to blame.

When scientists say that watching TV leads to diabetes, heart disease and premature death, it’s because those conditions are associated with higher levels of inactivity. Sitting still not only decreases our overall energy use, but it also has profound long-term effects.

A 2010 study found that being sedentary for two days leads to widespread changes in gene expression, including disruptions to energy-production—and the effects stuck around even after participants got moving again. What’s more, this spring researchers determined that sitting for most of the day—whether in the car, at work or in front of the tube—increases the risk of an earlier death. Since we tend to veg out on the couch while we watch TV, it’s no wonder that hours spent this way are linked to a wide variety of health problems, especially those associated with obesity.

TV-watching can also lead to bad eating habits. When we’re glued to the tube during meals, we eat more and have trouble recalling how much we’ve eaten, which can lead to consuming larger portions at other meals, even after we’ve turned off the television.

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The good news is that if you can’t live without your favorite shows, lessening TV’s unhealthy effect on your body is simple. Studies suggest, for example, that moving during commercials, like stepping in place or walking around, can reduce the negative effects of being couch-bound. Turning off the TV during meal times also goes a long way for the whole family.

Children are especially vulnerable to the adverse health effects of prolonged sitting. This is a real concern, given that more and more parents are turning to TV to settle down boisterous kids, thus lowering their overall daily physical activity. Because of this, the American Academy of Pediatrics discourages TV-viewing for children under the age of two, and states that older kids should be limited to no more than two hours a day—about half the daily TV-viewing of the average American child.

Scientists are much more split over whether what we watch has adverse health effects, especially on children. When it comes to kids, the real debate is whether the dangers of TV go beyond the health effects of being sedentary, including potential long-term impacts on their brains.

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The crux of the argument against kids watching TV is that time spent in front of the tube takes away from developmentally important activities like playing and socializing, which is true. There are a number of studies that find TV-watching is associated with poorer academic performance, including a 7 percent drop in classroom engagement for every hour of television a child logs in.

Yet many scientists argue that television is being unfairly victimized. There is a pervasive belief that watching TV as a child leads to attention disorders, despite a lack of evidence. Similarly, violent and sexual content is believed to lead to aggressive behaviors, though there is scant evidence to support the connection. And while some studies have shown a connection between TV-watching and poor grades, other studies have linked watching the tube to improved language skills and learning.

Research shows that not all programming is created equal. Adult programming negatively impacts infants’ language development, while children’s shows don’t. Even age-appropriate content can be a mixed bag. Some programs have been shown to increase language skills, while others, targeted to the same age group, do the opposite. The age of the viewer is also a factor. For example, “Sesame Street” has been shown to improve vocabulary development in 3- to 5- year-olds, but the effect wanes by six.

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Bottom line: As a parent, it’s important to monitor the kinds of shows your kids watch to make sure they’re age-appropriate, especially when it comes to younger kids. What’s more, limiting television-viewing likely provides a number of health benefits because it forces adults and kids to get off the couch and be more active.