As the U.S. launches its first-ever National Childhood Obesity Awareness Month today, scientists say the problem may be even more widespread than was thought. Researchers have found that parents tend to underreport their children's weight. Estimates of obesity and body mass index (BMI) based on parent-supplied data may miss one in five obese children.

This sobering news underscores the need for National Childhood Obesity Awareness Month. Congress established the observance in a resolution passed unanimously earlier this year, seeking to "raise public awareness and mobilize the country to address childhood obesity." A wide array of organizations have joined together as the National Council on Childhood Obesity Awareness Month, educating parents, policy makers and others about the problem and encouraging preventive action on childhood obesity. The new website includes a toolkit with fact sheets, sample letters to the editor, scripts for public service announcements and other resources.

Such advocacy is needed more than ever, in light of a study conducted by Daniel O'Connor, Ph.D., andJoseph Gugenheim, M.D. and presented in June at the 57th Annual Meeting of the American College of Sports Medicine. Researchers compared the measured height and weight of 1,430 children at an orthopedic clinic with the values their parents reported. "Parents tend to overestimate boys' height and underestimate girls' height," said O'Connor, "and this error was larger when the reporting parent was the opposite sex of the child. Almost half of the parents underestimated their child's weight, and errors in reporting weight tended to be larger for girls and increase with age." Ethnicity played a role, with African-American and Hispanic parents making larger errors than Caucasian, non-Hispanic parents, and weight errors were larger in children who were overweight or obese.

According to O'Connor, "The most striking finding was that using the parent-reported values to compute BMI and obesity status, following [Centers for Disease Control] guidelines, resulted in about one in five obese children – 21 percent – being missed in the count and not identified as obese."

Even without adjusting for underreporting, conventional estimates of childhood obesity are startling. During the past four decades, obesity rates have soared among all age groups, increasing more than fourfold among children ages six to 11. More than 23 million children and teenagers (31.8 percent) ages two to 19 are overweight or obese, a statistic which health and medical experts say constitute an epidemic.

The scope of the problem and its impact on health care costs and individual quality of life propelled Congress to take unanimous action. Congresswoman Marcia L. Fudge (D-OH) co-sponsored the House legislation with Congresswoman Kay Granger (R-TX). Rep. Fudge said, "Nothing can be more important than protecting the health and well-being of our children for years to come. I look forward to parents, health care providers, educators, civic leaders and organizations joining the effort to end childhood obesity." Rep. Granger said, "Childhood Obesity Awareness Month supports the goals of families, schools, and communities who are working to ensure we raise a healthier generation. If we keep our kids healthy now it will alleviate a major burden on our health care system while giving millions of young people the opportunity to live longer, healthier lives."

The National Council on Childhood Obesity Awareness Month encourages individuals and organizations to do whatever they can to build understanding of the causes and implications of childhood obesity and to earnestly seek solutions to stem the epidemic. While the focus now is on September as National Childhood Obesity Awareness Month, the effort must be sustained and widespread, according to organizers.