U.S. researchers said if a parent is worried about the weight of their child, the parents should lose weight themselves and their children will too.

Kerri N. Boutelle, an associate professor of pediatrics and psychiatry at University of California, San Diego, and Rady Children's Hospital-San Diego, and colleagues said 31 percent of U.S. children were overweight or obese -- between 4 and 5 million children.

"We looked at things such as parenting skills and styles, or changing the home food environment, and how they impacted a child's weight," Boutelle said in a statement. "The No. 1 way in which parents can help an obese child lose weight? Lose weight themselves. In this study, it was the most important predictor of child weight loss."

The study involved 80 parent-child groups with an overweight obese child ages 8-12, who participated in a parent-only or parent plus child treatment program for five months.

The study focused on evaluating the impact of three types of parenting skills taught in family-based behavioral treatment for childhood obesity: The parent modeling behaviors to promote their own weight loss, changes in home food environment and parenting style and techniques -- for example, a parent's ability to help limit the child's eating behavior, encouraging the child and participating in program activities.

The study published in the journal Obesity found, consistent with previously published research, parent body mass index change was the only significant predictor of child's weight loss. (UPI)