Experts generally consider BMI for kids to be a good measure of body fat, at least among heavier children. But in some cases it might be misleading. Athletic kids, in particular, may fall into the overweight category when they are actually muscular.

    Your child's BMI is important, but it is only a piece of the picture. If a BMI percentile (体重指数) indicates that your child is not within the healthy range, she needs a complete weight and lifestyle evaluation with a doctor.

    Experts recommend that kids of all ages and all weight categories follow these healthy guidelines to keep weight in control. It's easy to remember them as “5 — 2 — 1 — 0” every day.

    5 > Everyone in your family needs five servings of vegetables and fruit. Keep serving them even if kids don't eat them. If they see a food over and over, they're more likely to try it in the end.

    2 > Limit TV-watching to no more than 2 hours a day. Family members who use other “screens”—video games or computers, for instance, get less TV time. And kick the TV out of all bedrooms.

    1 > Get 1 hour of physical activity. Add up the minutes each family member is moving —it should be 60 minutes or more for each person. Start small and keep adding if necessary.

    0 > That's how many sugar-sweetened beverages you should have a day. Juice drinks such as lemonade and fruit punch, sodas, tea, and coffee can all have added sugar. Stick to water and reduced-fat milk instead.