Fighting the battle against childhood obesity has to start with the children themselves. A new report claims that this could be harder than it seems, since many overweight kids don’t even realize they have a weight problem.

The Centers for Disease Control and Prevention’s National Center for Health Statistics compiled government data covering about 6,100 kids and teens age 8 to 15. The resulting report demonstrated that about 30 percent of these children and teens “misperceived” their weight status.

According to the CDC report, of the kids and teens who were designated as overweight based on government guidelines (between the 85th and 95th percentiles on the CDC’s growth chart), 76 percent thought their weight status was “about right.” Only 23 percent correctly identified themselves as overweight. Among the young people above the 95th percentile on the chart, about 42 percent thought their weight was fine and 57 percent felt they were overweight.

The report also concluded that boys, younger kids and children from lower-income families were more likely to wrongly identify their weight status.

Even so, some experts warn against labeling children and teens as overweight. “Shame is a terrible motivator,” says Marlene Schwartz, a psychologist and director of the Rudd Center for Food Policy & Obesity at Yale University. Her advice to parents is to focus on giving kids feedback about their nutrition and activity choices, rather than demanding they hit some number on a scale to be at the “right” weight.