Sculpted arms without breaking a sweat? Two minutes a day to chiseled abs? Teens preoccupied with defined muscles or attempting to gain weight were more likely to take potentially harmful supplements at least weekly, report researchers in a new study in Pediatrics.

Girls trying to look like women in the media and boys who perused fashion, health, and men's magazines were also more likely to take such products regularly, including weight loss drinks, protein powders and shakes, creatine, amino acids, growth hormone, and steroids.

Among the other findings of this study of over 10,000 teens:

• About a third of both boys and girls reported often thinking about or desiring toned muscles.
• About 12 percent of boys and 8 percent of girls had used potentially unhealthful products in the past year, and about 5 percent of boys and 2 percent of girls used them at least weekly. The most popular supplements reported were protein powders and shakes.
• Slightly less than half of boys and a little over a third of girls described themselves as being happy with their bodies.

"Unless you know something is safe, it's best to avoid it," says Alison Field, an epidemiologist at Children's Hospital Boston and primary author of the study. Field says that although protein powders and shakes are probably safe and the side effects of steroids are well documented, the health consequences of many of these supplements are unknown.

In 1999, researchers sent questionnaires to 12-to-18-year-old participants in the ongoing Growing Up Today Study, which follows some of the children of nurses enrolled in the Nurses' Health Study. Teens answered questions about their height, weight, exercise habits, body image, media exposure, and use of body-enhancing supplements.

Field encourages parents of both boys and girls to be "more informed consumers" about the media's portrayal of "unattainable looks."

"We tend to think of weight concerns being a female issue," says Field. "It's striking how many boys were thinking about toned or defined muscles."