From Liz Atwood: For years we’ve heard about the teen and tween girls who have a negative body image. Trying to emulate the unnaturally thin models they see on TV or in magazines, they can starve themselves to death.

But a new study shows that not only girls, but also teen and tween boys, can harm their health when they become too worried about their bodies.

The journal Pediatrics recently published a study that shows a significant number of boys are using protein shakes and steroids to build their muscles. More than a third of the high school and middle school boys in the study reported using protein shakes; nearly 6 percent said they used steroids. Even more shocking, nearly as many middle schoolers as high schoolers reported using steroids.

The researchers urge pediatricians to be on the lookout for these risky behaviors in their patients. Parents, also, need to be aware. We want our children to watch what they eat and get plenty of exercise. But the kids need to know that using performance enhancers to change their bodies can have serious consequences.