HealthDayNews -- If your child is at high risk for being overweight or obese, restricting food probably isn't the best way to try to keep the youngster at a healthy weight.

That's because in children who have a genetic predisposition to gaining extra weight, parental restriction of food may actually cause them to gain more weight, says a study appearing in the October issue of Pediatrics.

"There's a lot of controversy because some studies have found a relationship between more restrictive feeding style and heavier kids," said study co-author Myles Faith, from the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine.

"But, it's the chicken and the egg question. Is it the parent's restrictiveness causing the child not to know when he's hungry or full, or is it that a parent sees an overweight child and decides to restrict what he's eating?" asked Faith. "Or could it be both?"

In this study, the researchers found that restricted eating was really only a problem in children whose mothers were overweight at the start of their pregnancy, which Faith said is a good indicator of a child's genetic risk for being overweight.

He added, though, that parents are probably restricting food, in part, as a response to their child's increasing weight.

"It might be a bi-directional relationship, because parents don't behave in a vacuum. They respond to children's behaviors and characteristics. The concern, though, may be excessive restriction," said Faith.

Faith and his colleagues studied 57 families to see how parental feeding styles affected the child's weight. All of the families were white and from Pennsylvania.

The children were classified as either high risk or low risk for obesity based on their mothers' weight. Their weight and height measurements were taken at ages 3, 5 and 7 so that their body mass index (BMI) could be calculated.

Parents were given a questionnaire designed to identify their feeding styles and attitudes when their children were 5, and then again when the kids were 7.

The researchers found that parents' feeding styles didn't change much during the two-year study period. More importantly, they found differences between high-risk and low-risk children in the way they responded to parental feeding styles.

High-risk children were much more likely to have an increased BMI at the end of the study if their parents restricted food. The authors suggest this shows a relationship between genes and the environment when it comes to obesity.

Faith suggests that, rather than excessively restricting foods, parents should actively promote healthy food choices, make healthy food available, and model good eating behavior themselves.

But getting kids to eat healthy isn't easy in today's environment, acknowledged Sally Ann Lederman, a research associate at the Obesity Research Center at St. Luke's Hospital of Columbia University in New York City and one of the authors of a supplement on preventing childhood obesity in the same issue of Pediatrics.

"The childhood obesity problem is caused by a confluence of factors," she said. Chief among them is the supersizing of portions, soda drinking, and the lack of physical activity. She pointed out that between TV and computers, youngsters today spend hours on "screen" time every day that would be better spent doing some sort of physical activity.

"That probably would have been enough to cause a problem on its own, but now food is available at every turn also. People are always eating when they're not hungry," Lederman said.

"It's a synergistic relationship. If you had this availability of food, but kids were out running around and expending energy, it wouldn't be as big a problem," she said.

"There's no simple answer, and that's why it's gotten as bad as it has," she said.

Lederman said that most parents need to change their own lifestyles if they want their children to be healthy. The most important thing for both parent and child is to get moving. "Get your kids up off their butts," she advised.