The maxim holds true: too much of anything is bad for you. Common Sense Media, a nonprofit advocacy group, and researchers from the National Institutes of Health, Yale University and California Pacific Medical Center have published a report that draws links between media consumption and children's health. After reviewing 173 studies in various categories, the researchers found that the more TV, movies, music and technology a child is exposed to, the higher the health risks they face. TIME spoke with Stanford University professor James Steyer, founder of Common Sense Media, about how parents can keep their kids on the media straight and narrow.

It seems that the takeaway from this report is that heavy consumption of media makes kids fatter, more likely to smoke, use drugs and get bad grades. Is that the sum of it?

Basically. Too much bad media can be hazardous to your child's health. What we wanted to do was not just take a look at one connection between media and health, say, childhood obesity or sexual behavior. We wanted to conduct a meta-study, a comprehensive look at all different aspects of the way media affects children. And the bottom line is that it can have a significant impact in the areas we looked at: childhood obesity, tobacco use, sexual behavior, drug use, alcohol use, low academic achievement and ADHD. [Lead researcher] Dr. Ezekiel Emanuel and his team looked at thousands of studies, and then picked the 173 best. In the areas that were graded high—obesity, drug use and sexual behavior—it was clear that media was a contributing factor to negative outcomes in those three categories.

When you say "media," what exactly are you talking about? Your report mentions that the researchers weren't able to get much data on "new media."

When we refer to media at Common Sense, we're talking about everything from Internet and cell phones and video games and social networking sites to traditional media like movies, TV, music and books. What we found in these studies, however, is that there's almost no research on new digital media, on social networking platforms, on Internet usage, on how kids text message. That's one of the conclusions we draw in this report. There's a tremendous need from a public health standpoint to do research on these areas, because they will affect public policy and basic good parenting behavior.

Most studies on kids and media focus on violence. Why did you avoid that here?

Zeke [Dr. Emanuel] and the research team decided that there was a voluminous amount of studies that focus solely on media and violence. So they wanted to stay away from that. Now, with our report, there are two important words to distinguish between: correlation and causation. This report doesn't say, nor would Common Sense ever suggest, that media is the cause of all society's ills, or the sole cause of childhood obesity or risky sexual behavior or smoking or alcohol use among teens. But it is a significant contributing factor. That's different from saying it's the sole cause. And a very important thing to say up front is that we're not anti-media. I'm a first-amendment law professor at Stanford. Our motto is sanity, not censorship. We want you to know what the impact of media can be, both positive and negative.

You were in Washington the other day briefing policy makers on the report. What sense did you get from them?

Obviously, Zeke's brother [President-elect Barack Obama's chief of staff, Rahm Emanuel] will have a strong position in the incoming Administration. And I am optimistic that you'll see a renewed emphasis, from the White House on down, on media, technology and kids. In that sense, I'm very hopeful that Barack and Michelle Obama will be parents-in-chief and role models-in-chief for our country. Barack talked about it repeatedly through his campaign—turning off the TV, turning off the video games, doing your homework, talking with your kids.

What are your general recommendations, then, for parents, based on this study?

Parents are the first line of defense. You have to be involved in your kids' media lives today, just like you go to their parent-teacher conferences, like you help them with your homework. The average kid spends almost 7 hours a day consuming some sort of media, so you have to be involved in setting clear limits and balanced amounts of time that kids can spend with different forms of media. That's as true for video games and cell phones as it is for TV and movies.

Kids get so many values and messages from media. As a parent, you've got to have a dialogue with them about that. Whether you're talking about sex or violence or commercialism, a lot of the messages kids are getting come from the media. So you have to have an open dialogue. And you have to be a savvy media consumer yourself, so you know what they're experiencing.