One third of American children and youth are obese, or are at risk of becoming obese, a recent national Institute of Medicine report said.

Parents cannot always tell just by looking at their children, however, if they are overweight. Children, like adults, come in all different shapes and sizes. That paunch, says Alice Lindeman, an associate professor in the Department of Applied Health Science at Indiana University, could be a sign that a child needs to lose some weight or that a growth spurt is just around the corner.

"They get tired, they get cranky, they get these little paunches, and then they grow," she said. 

Pediatricians track children's growth from birth and can help parents recognize whether their children are overweight or anticipating a growth spurt. Lindeman said the combined approach of increasing activity levels and creating a healthier lifestyle is the best way to help overweight children achieve a healthy weight, but it also means the child won't be going it alone. Healthy eating habits and other lifestyle changes should be adopted by the whole family to be effective.

"Don't tell them to be active and then sit and read a book, that's not right," Lindeman said. "Get up and play with them."

Lindeman offered the following suggestions:

• Mirror each other's behavior. Don't tell your child, for example, that she can eat only six M&Ms while you munch on 60. "If you don't want them to go back for seconds, you shouldn't go back for seconds," Lindeman said.

• Create an environment that applies to everyone in the family and maintains a healthy lifestyle for all. This will help prevent any one child from feeling singled out.

• Teens get at least 25 percent of their calories from snacks and possibly as much as 50 percent. Lindeman says snacks should include two food groups, not just one, to provide more balanced nutrition. "If you're going to have pretzels, how about some peanut better? If you're sensitive about glucose fluctuations, including protein in your snack, with such foods as yogurt, milk or lunch meat, can help keep glucose levels from jumping," she said. Meals should include three food groups.

• Talk to your children about hunger are they really hungry for seconds?

• Parents should put the child's food on the plate so they can control the serving sizes. Eat at the table, not in front of the TV or standing. Take time to eat slowly, rather than wolfing down meals. Children can make a game out of eating slowly. They can, for example, eat a cookie in circles, taking tiny bites.

• Some structured diets, such as Weight Watchers, have children's versions. Lindeman said parents should talk with their child's pediatrician before starting them on such diets.

For information on Indiana University Bloomington's School of Health, Physical Education and Recreation, visit www.hper.indiana.edu.