“There are some males who do want to be thinner and are focused on thinness,” Field says, “but many more are focused on wanting bigger or at least more toned and defined muscles. That’s a very different physique.”

If boys are increasingly concerned about weight, changing representations of the male form in the media over the last decade or two are at least partly to blame. “We used to really discriminate—and we still do—against women” in terms of media portrayals, says Dr. Raymond Lemberg, a Prescott, Arizona-based clinical psychologist and an expert on male eating disorders. “If you look at the Miss America pageant winners or the Playboy centerfolds or the runway models over the years, there’s been more and more focus on thinness.”

But while the media pressure on women hasn’t abated, the playing field has nevertheless leveled in the last 15 years, as movies and magazines increasingly display bare-chested men with impossibly chiseled physiques and six-pack abs. “The media has become more of an equal opportunity discriminator,” says Lemberg. “Men’s bodies are not good enough anymore either.”

Even toys contribute to the distorted messages youngsters receive about the ideal male form. Take action figures, for example, which Lemberg suggests are the male equivalent of Barbie dolls in terms of the unrealistic body images they set up for young boys. In the last decade or two, action figures have lost a tremendous proportion of fat and added a substantial proportion of muscle. “Only 1 or 2 percent of [males] actually have that body type,” says Lemberg. “We’re presenting men in a way that is unnatural.”

In the face of the ideals they’re bombarded with, it’s no surprise that adolescent boys, like waves of girls before them, are falling prey to a distorted image of themselves and their physical inadequacies: Previous research suggests that up to 25 percent of normal weight males nevertheless perceive themselves to be underweight.

And given their perception of themselves as too small, it’s also no surprise that boys are searching out means to bring their bodies into conformity with the muscular ideal. A 2012 study of adolescents revealed that muscle-enhancing behaviors are pervasive among both middle school and high school-age males: More than a third reported downing protein powders or shakes in an effort to boost their muscularity; in addition, almost 6 percent admitted to using steroids and 10.5 percent acknowledged using some other muscle-enhancing substance.

Pharmaceutical-grade injectable steroids are a definite concern, says Dr. Rebecka Peebles, co-director of the Eating Disorder Assessment and Treatment Program at the Children's Hospital of Philadelphia, but they’re not the biggest worry, given that they’re difficult to obtain. Of more concern are the “natural” powders or shakes that teens can pick up at their local GNC. The problem, Peebles says, is that “natural” in this case simply means unregulated. “They actually can include all kinds of things in them,” says Peebles. In some cases powder or shake supplements “are actually anabolic androgens and just packaged as a natural supplement.”