Take David Abusheik. At age 15, he started lifting weights for two hours a day, six days a week. Now that he is a senior at Fort Hamilton High School in Brooklyn, he has been adding protein bars and shakes to his diet to put on muscle without gaining fat.
"I didn't used to be into supplements," said Abusheik, 18, who plans on a career in engineering, "but I wanted something that would help me get bigger a little faster."
Pediatricians are starting to sound alarm bells about boys who take unhealthy measures to try to reshape their bodies into ones, like the actor Channing Tatum's, that only genetics can truly confer. Whether it is long hours in the gym, allowances blown on expensive supplements or even risky experiments with illegal steroids, the price American boys are willing to pay for the perfect body appears to be on the rise.
In a study to be published Monday in the journal Pediatrics, more than 40 percent of boys in middle school and high school said they regularly exercised with the goal of increasing muscle mass. Thirty-eight percent said they used protein supplements, and nearly 6 percent said they had experimented with steroids.
Overall, 90 percent of the 2,800 boys in the survey - who lived in the Minneapolis/St. Paul area, but typify what doctors say is a national phenomenon - said they exercised at least occasionally in order to add muscle.
"There has been a striking change in attitudes toward male body image in the last 30 years," said Dr. Harrison Pope, a psychiatry professor at Harvard who studies bodybuilding culture and was not involved in the study. The portrayal of men as fat-free and chiseled "is dramatically more prevalent in society then it was a generation ago," he said.
While college-age men have long been interested in body building, pediatricians say they have been surprised to find that now even middle school boys are so absorbed with building muscles. And their youth adds an element of risk.
Just as girls who count every calorie in an effort to be thin may do themselves more harm than good, boys who chase an illusory image of manhood may end up stunting their own development, doctors say, particularly when they turn to supplements - or worse, steroids - to supercharge their results.
"The problem with supplements is they're not regulated like drugs, so it's very hard to know what's in them," said Dr. Shalender Bhasin, a professor of medicine at Boston Medical Center. Some contain anabolic steroids, and even high-quality protein supplements might be dangerous in large amounts, or if taken to replace meals, he said. "These things just haven't been studied very well," he said.
Anabolic steroids pose a special danger to developing bodies, Bhasin said. Steroids "stop testosterone production in men," he said, leading to terrible withdrawal problems when still-growing boys try to stop taking them. Still, the constant association of steroids with elite athletes like Lance Armstrong and Barry Bonds perpetuates the notion that they can be managed successfully.
Online, in bodybuilding forums for teenagers, boys barely out of puberty share weight-lifting regimens and body fat percentages, and judge one another's progress. On Tumblr and Facebook, teenagers post images of ripped athletes under the heading "fitspo" or "fitspiraton," which are short for "fitness inspiration." The tags are spinoffs of "thinspo" and "thinspiration" pictures and videos which have been banned from many sites for promoting anorexia.
"Lifted b4 school today felt good but was weak as hell," wrote one boy who said he was 15 and from Tallahassee, Fla., on a message board on Bodybuilding.com in September, saying that he bench-pressed 245 pounds. "Barely got it."
Many of these boys probably see themselves in Mike Sorrentino, "The Situation" from the "Jersey Shore" series on MTV, or the Adam Sackler character, on the HBO series "Girls," who rarely wears a shirt or takes a break from his crunches.
Abusheik, for instance, has a Facebook page full of photos of himself shirtless or showing off his six-pack abs. At his high school, participation in the annual bodybuilding competition hit an all-time high of 30 students this year.
"They ask us about everything," said Peter Rivera, a physical education teacher at Fort Hamilton High School who helps oversee the competition. "How do I lose weight? How do I gain muscle? How many times a week should I work out?" Some boys want to be stronger for sports, Rivera said, but others "want to change their body type."
Compared with a sedentary lifestyle of video games and TV, an obsession with working out may not quite qualify as a health hazard. And instructors like Rivera say that most boys are eager for advice on the healthiest, drug-free ways to get in shape.
With so little known about supplements, it can be difficult, particularly for teenagers, to make wise decisions.
Alonso Huizar, 16, of Tucson, Ariz., could not say for sure which creatine supplements he takes. "I bounce around," he said. "I get like, some type of chocolate flavor, depending on the price."
Alonso started lifting weights at 15 because he wanted to get bigger for soccer, "but I was also just trying to gain weight in general," he said. Cristiano Ronaldo, the Brazilian soccer player, is the man with the body he would like to have, he said.
His mother, Ana, said she would have preferred that Alonso hold off on weight training until he was older, but the pressure from coaches and peers made compromise impossible. "It's pushed on them - if you're going to play soccer, you have to lift weights," she said.
Boys are not alone in their pursuit of muscularity. A majority of girls in the Minnesota study said they had changed eating or exercise habits to build muscle, with 21 percent using protein supplements and nearly 5 percent using steroids.
"The model of feminine beauty is now more toned and fit and sculpted than it was a generation ago," said Marla Eisenberg, assistant professor of pediatrics at the University of Minnesota, the lead author of the Pediatrics study. "It's not just being thin, it's being thin and toned." Indeed, visitors to the "Fitspo" Facebook page are greeted by a sinewy model wearing a tank top that reads "Strong is the new skinny."
Paradoxically, the emphasis on weight lifting among adolescents may be depleting the number of contestants in teenage bodybuilding meets, because many children can't pass a drug test.
"You used to get a lot of teenage bodybuilders, but you don't get them as much anymore," said Andrew Bostinto, president of the National Gym Association. "A lot of these kids are juiced, so they're not entering natural shows."
"You get these kids now, they're 5 feet 6 inches, 5 feet 7 inches, weighing 265 pounds with two percent body fat," he said. "Give me a break. You can't put on 30 pounds in a month."
Abusheik, who stands 5 feet tall and weighs 125 pounds, said he steered clear of steroids and would prefer not to use supplements. But because of his small stature, he needed the extra bulk to compete in his school's bodybuilding contest.
"I'm mostly trying to get into engineering," he said, "but if something gets in the way I figure I can always be a personal trainer."