All those glossy magazine ads showing men – and women – with bulging muscles may be having a big impact on America’s youth.  In a new study of 2,793 teens from 20 urban middle and high schools, more than 90 percent of boys and 80 percent of girls said they were exercising to become more buff.

If exercise was the only method kids were using to pump up their muscles, it wouldn’t be a problem. But a large number of American teens are also using protein powders and other methods to help them bulk up, researchers reported. And even more concerning, almost 6 percent of boys and 5 percent of girls were turning to steroids to achieve the toned up look they craved, according to the study published Monday in Pediatrics.

What’s troubling, the researchers say, is the possibility that as they grow older, more and more teens will turn to unhealthy methods to muscle up.

“If they’re interested in developing muscle at 13, 14, and 15, what are they going to be doing at 18 or 20?” says the study’s lead researcher Marla Eisenberg, an assistant professor in pediatrics in the division of Adolescent Health and Medicine at the University of Minnesota School of Medicine. “Are they going to be doing something more dangerous?”

The researchers were surprised at the number of girls who were hoping to bulk up. That certainly signals a change in what American teens see as the ideal female body.

“The ideal figure for women for a long time was very thin,” Eisenberg says. “Now more and more we’re seeing images of women who are not just slender, but also have toned shoulder and arms. They’re very fit looking.”

For the new study, Eisenberg and her colleagues surveyed adolescents from 20 middle schools and high schools in the St. Paul/Minneapolis area of Minnesota. The teens, whose average age was nearly 14 and a half (14.4), were asked to fill out a 235-item questionnaire.

The questionnaire looked at attitudes and behaviors relating to weight and appearance.

Particularly telling were the answers to this question:  

“How often have you done each of the following things in order to increase your muscle size or tone in the past year? (a) Changed my eating (b) Exercised more (c) Used protein powder or shakes (d) Used steroids (e) Used another muscle building substance (such as creatine, amino acids, hydroxyl methylbutyrate, DHEA, or growth hormone).”

The possible answers were: never, rarely, sometimes, often.

More than two thirds of boys said they had changed the way they ate to muscle up, while more than 90 percent said they were exercising to add muscle, 40.9 percent saying they did this often. Similarly, nearly two thirds of girls said they’d changed their diets and more than 80 percent girls said they were exercising to tone their muscles.

Among the boys, 34.7 percent were consuming protein powders or shakes, 5.9 percent reported using steroids, and 10.5 percent said they were using some other muscle enhancing substance. That’s compared to 21.2 percent of girls using protein powders or shakes, 4.6 percent taking steroids, and 5.5 using some other muscle enhancing substance.

Those numbers concern Dana Rofey, an assistant professor of pediatrics in the Division of Weight Management and Wellness at the Children’s Hospital of Pittsburgh.

“I am quite surprised at the prevalence of protein powders and shakes and steroid use,” Rofey says.

While it’s good that young people are trying to get in shape, there could be a dark side to all this bulking up if kids take it too far, Rofey says.  

A study like this should serve as a warning call to parents, she adds. 

“I always tell my patients’ parents, you can never underestimate your role in terms of role modeling,” she explains. “I have two young daughters myself. Sometimes I have to stop and explain to them why I’m working out. Why I’m doing all those ab exercises.

"You need to talk openly with them about the importance of being healthy and of not doing fad kinds of things to look a certain way.”

For her part, Eisenberg hopes that people will understand that fitness is a good thing, but you have to achieve it through healthy means.

“We definitely don’t want to be taken as trying to send the message that exercise or eating in a certain way is bad,” Eisenberg says. “There are many good things that go along with those behaviors, such as general fitness and health. We’re concerned that when achieving a certain physical appearance is the driving force, those good behaviors might give way to less healthy ones in the future.”