By Dale Dunlap

It’s 10 p.m. - do you know what your teenager has eaten today?

We are used to worrying about our own weight but now are facing a new challenge: our children’s eating habits and lack of exercise. According to the U.S. Centers for Disease Control, more than 30 percent of American youth ages 6 to 19 are overweight and more than 15 percent are obese.

The food choices our children are making now may have lasting effects beyond obesity. About half the body’s bone density is formed during teen years. Teens should eat more calcium- and iron-rich foods during this critical time.

Knowledge is power. Give your children the power to make wise choices. A recent study conducted by Penn State University found that in high schools that posted food values in the cafeteria, teens more often chose foods lower in fat and calories.

Knowing that weight-bearing exercises help increase bone density and resting metabolic rate (the amount of calories burned at rest) may motivate teens, especially those whose weight is a problem. An even greater motivator for teens may be learning that a healthy diet and exercising regularly will improve the way they look and feel.

Eliminating only one junk food a day can greatly reduce calorie consumption per week. Regular short periods of exercise also add up.

Plan for success by implementing these basic strategies:

• Stock the refrigerator with healthy foods, especially produce and fruit. Involve your children in making a grocery list.

• Don’t keep snack foods and soda on hand. Instead, stock healthy foods that are easy to see and reach.

• Set aside time to walk or bike with your child. This is a great way to spend time chatting about the day’s events as you are establishing healthy life habits. Encourage kids to ride their bikes instead of driving. Making them chip in for gas money can help influence the mode of transportation they choose.

• Limit sedentary activities such as watching TV, playing video games and sitting at the computer.

You know that setting a good example is important, but let’s face the reality of life in Silicon Valley - our lives seem to become more hectic and over-scheduled with each passing day. Trying to find a time when we can sit down with our children for a meal or go for a walk or ride is challenging.

The good news is that our children understand that we are not perfect even while they look to us for guidance and support.

The further good news is that small changes really do add up. Adolescents and teens usually make better food choices when informed and involved in the selection. Combining exercise and a healthy diet will produce positive results in the way your teen will look and feel today, and healthy habits formed in childhood that are encouraged and supported can last a lifetime.

Dale Dunlap owns Custom Fitness, 650 Castro St., Mountain View. Visit www.custom-fitness.com for more information.