Dear Mr. Dad: I’m concerned about my 12-year-old son. He’s been putting on a lot of weight lately and I’m worried that he’s going to develop some serious health problems. I’ve tried to interest him in doing more physical activity, but it doesn’t seem to work. How do I keep my kid from becoming just another statistic?

A: First of all, you deserve a big round of applause. Recent studies have found that over 60 percent of parents of overweight 10-12-year-olds don’t think their child has a problem. Neither do about 90 percent of parents of overweight 4-8 year olds. The fact that you’re concerned is wonderful.

Childhood obesity is a big problem—and it’s getting worse every day. Over the last three decades, overall obesity rates for children doubled. For adolescents, the rate tripled. Today, a third of kids 10 to 17 are overweight—half of them qualify as obese. Overweight and obese kids have an increased risk of developing high blood pressure, high cholesterol, respiratory and orthopedic problems, and Type 2 diabetes. That’s while they’re still kids. Over 80 percent of obese children become obese adults, and those health problems become even more dangerous. There’s also evidence that obesity also affects kids in non-life-threatening ways, including their academic performance, social development, and even their career success.

Your first order of business is to get your son to a doctor. This is important for a number of reasons. He or she will be able to tell exactly how overweight your son actually is. Children go through growth spurts, and often put on a bit of extra weight before shooting up in height. There’s also a chance—albeit a pretty slim one—that you’re wrong about your son and making a mountain out of a molehill.

Next on the list is to make sure your child is getting enough exercise. Current recommendations are that all of us—adults and children—should get an hour of sweat-inducing exercise every day. Unfortunately, less than a third of children 6-17 get even 20 minutes/day. And don’t count on your child getting that exercise at school. Budget problems have reduced or eliminated many physical education programs.

Limiting TV and video game time is critical. The Kaiser Family Foundation recently found that kids 8-18 spend an average of six hours/day in front of one kind of screen or another. While some of that time is clearly important, a lot isn’t. So let your son earn his screen time by putting in an equal amount of hours doing physical activity. If he balks, at least pick up some games for whatever device you have (X-Box, Wii, etc). Some of the new motion-sensing titles may be more successful in getting your son off the couch than you are.

Of course you should pay attention to your son’s diet, but don’t forget about his drinks. We all know that sugary sodas are bad news. But fruit juice isn’t much better. You can minimize problems by insisting on regular (and healthy) family dinners, a good breakfast, drinking more water, and banning junk-food snacks from your home. Also, make sure your son gets enough sleep—9-10 hours/night. Less than that increases his obesity risk.

Finally, take a look at your own behavior. Are you practicing what you’re preaching? At 12, your son is paying more attention to what you do than what you say. But your words are still important. So rather than focus on his weight, talk to him about his health. Coming down too hard could backfire and make the problem worse.