Durham, N.C. - Childhood obesity is a growing national health crisis. The number of overweight or obese children has increased by more than 50 percent since the mid-1980s. New studies are finding that the problem starts early. An estimated 10 to 15 percent of preschoolers are overweight and show early warning signs of diabetes by age five. Jennifer Cheng, assistant clinical professor of pediatrics at Duke University Medical Center, says it's easy to fault parents and fast food chains for the problem, but it's a much more complex issue.

"Often there is a financial barrier. Parents cannot necessarily purchase the healthier choices in food because it's just cheaper to go get a Happy Meal. In addition, a lot of people live in unsafe neighborhoods, so there aren't a lot of options as far as getting children to be physically active."

Cheng says there are positive signs in the campaign against childhood obesity, such as chains offering low-fat milk as an alternative to soda on kids' menus. She says parents can take some basic steps to prevent their children from becoming overweight: limit junk food, eat meals together, encourage physical activity and, above all, be a role model: eat healthy yourself.

I'm Cabell Smith for MedMinute.