'Parents have to help teens understand that they're comparing themselves to an image that isn't real.'

Based on a nationwide survey of more than 10,000 adolescents, the study, out today in the journal Pediatrics, shows a high rate of concern about body image in both boys and girls and finds that teens who worry about body image are much more likely to use hormones and dietary supplements to try to enhance their physiques.

Potentially Unhealthy Products

Almost 5% of teenage boys and 2% of girls use potentially unhealthy products ranging from protein powders to growth hormone and injectable steroids at least weekly to improve appearance or strength.

"The take-home message here is that we really need to think about body-image dissatisfaction in boys as well as girls," says Alison Field, a Harvard Medical School professor of pediatrics and lead researcher on the study.

"Both are influenced by the images they see in the media, which can be unrealistically thin for girls and unrealistically muscular for boys."

The research was conducted using data from Harvard's ongoing study titled Growing Up Today. It includes 6,212 girls and 4,237 boys ages 12 to 18.

Figures in the Media

Teens who told researchers they "frequently" thought about wanting more defined muscles and made a lot of effort to look like figures in the media were more than three times as likely as peers to use products to build muscle or improve their appearance.

The most commonly used products were protein powders and shakes. Others, used mostly by boys, included creatine, amino acids, the amino-acid metabolite HMB, the hormone dehydroepiandrosterone (DHEA), growth hormone and anabolic steroids.

Protein powders are probably relatively safe, but steroids have known health effects, and much less is known about creatine and growth hormones, particularly in young people, Field says.

"You really don't want them using anything unless you know it's safe," she says.

Weight-Obsessed World

As Americans overall become fatter and further away from the thin, toned body that society considers ideal, teens increasingly are turning to extreme behaviors to achieve what often is unachievable, says Dianne Neumark-Sztainer, an epidemiologist at the University of Minnesota and author of I'm, Like, So Fat! Helping Your Teen Make Healthy Choices About Eating and Exercise in a Weight-Obsessed World.

For example, images of male models in advertisements are often shaded to make their bodies look as if they have more muscle definition, Field says. "Parents have to help teens understand that they're comparing themselves to an image that isn't real."