Unfortunately, a lot of kids today spend the vast majority of their time at home in front of the tv or computer. And, their parents do too. According to most studies, adults are also spending more time in front of the tv.

The link between too much “screen time” and obesity is well documented. Study after study has shown that our kids are spending more time watching tv, playing video games, and sitting at the computer. And, they are heavier than ever.

Kids who regularly watch four or more hours of tv per day are more likely to be overweight. (At first blush, four hours seems like a lot, but when you think about a child watching an hour or so in the morning, an hour after school and two hours later in the evening, it doesn’t seem so crazy outrageous.) It’s widely accepted that more time in front of the tv or computer increases one’s odds of being overweight.

Most of the research that’s been done in this area suggests that screen time causes obesity (at least what I’ve read). Makes sense. You’re sitting there like a big lump and then you become a big lump.

Still, I wonder if there’s another possibility. Could we have this whole thing backwards? Perhaps the increase in tv time is a symptom rather than a cause.

Obviously, screen time isn’t active. Participating in sports, playing outside or even playing board games does more to build healthy bodies than watching tv. While plopped in front of the tv, kids burn fewer calories and are also more likely to snack (fast- and junk-food commercials don’t help). The result is weight gain.

But what if kids watch so much tv because they have low energy to begin with? What if the food they eat leaves them without the energy they need for other activities?

Is screen time the chicken or the egg?

Why do kids watch so much tv nowadays? It’s often suggested that parents use the tv as a babysitter. Parents are either busy with other things or off at work, and the kids are left in front of the tv. While this may be the case in some families, most of the parents I know are far more involved in their children’s lives (and concerned about their children’s health) than parents of my generation. Not that my parents weren’t concerned, they just weren’t as consumed with childrearing as we seem to be today. Someone coined the phrase helicopter parents to describe the way we hover around our children. Whether or not the term describes you, chances are you are more involved in your child’s schedule, school work, and other activities than your parents were involved in yours.

So, what’s going on? Could it be that we are all watching more tv because we’re eating a bunch of crap that leaves us with little energy?

Consider this: Americans eat more processed food than anyone in the world at any time in the world. The average American eats 31% more processed food than fresh food. A 2005 study found that 90% of the money Americans spend on food is spent on processed foods.

While most of us ate processed foods growing up, there wasn’t the plethora of processed food options there is today (and there was no such thing as high fructose corn syrup, genetically modified crops, etc). (The processed food industry really took off after World War II as our culture became more consumer-based and has been growing ever since.) Eating this much processed food is a relatively new phenomenon.

Processed foods provide less nutrition than whole foods, tend to be high in salt and sugar, and also contain preservatives and other chemical additives. Because they contain a lot of simple sugars, processed foods cause a quick increase in blood sugar followed by a crash. The crash leaves us feeling depleted and tired. Combined with the lack of nutrition, it’s no wonder we’re all feeling rather sluggish.

And there’s not a lot I want to do when I’m feeling depleted, tired and sluggish. Except, of course, watch tv.

What do you think? Is screen time the chicken or the egg?