JOHN YANG: For years, eating disorders were thought to be a condition predominantly affecting women and girls.

But it's estimated that one in three people with an eating disorder is male, and that 10 million American males will struggle with it at some point in their lives.

Dr. Jason Nagata is a pediatrician specializing in eating disorders at the University of California San Francisco.

He's also editor of the book eating disorders in boys and men.

Dr. Nagata, do eating disorders look different in boys than in girls?

DR. JASON NAGATA, University of California, San Francisco: Yes, absolutely.

The masculine body ideal is big and muscular.

And that can lead to muscle building behaviors, like access to exercise, restriction of carbon and fats whilst over consuming protein and use of muscle building supplements and drugs like anabolic steroids.

When taken to the extreme, this can lead to muscle dysmorphia, also known as reverse anorexia or bigorexia.

And this is when somebody pathologically becomes obsessed with the idea that their body is too puny or scrawny, and they need to become more muscular.

JOHN YANG: What does over exercise, too much protein not enough carbohydrates?

What does that do to the body?

JASON NAGATA: In simple terms, we need to maintain an energy balance.

So whatever energy we're burning through physical activity or exercise, we need to take in and up for nutrition.

I think it's pretty well recognized that when people restrict their eating, like if they're skipping meals, or really eating a small amount of calories, that can lead to energy deficit.

But I think it's relatively under recognized that if people are exercising a lot, but not increasing their nutrition that can also lead to energy deficits.

And this is what we see in many of the boy athletes who develop eating disorders that we take care of.

JOHN YANG: We're hearing much more about eating disorders and boys.

Is it because there are more males with eating disorders?

Or is it just being recognized more and diagnosed more?

JASON NAGATA: I think it's a little bit of both.

The boys have more pressures for muscularity now more than ever.

Halloween (ph) superheroes have become more muscular than in past decade, boys action figures are more muscular.

And with the advent of social media, boys' bodies are on display more than ever.

And there are all these studies that have shown that more engagement with social media is linked with disordered eating, muscle dissatisfaction, and even steroid use, particularly among teenage boys.

I think the last factor is that the COVID-19 pandemic really led to an explosion of eating disorders among teenagers across the board including boys, too, due to a perfect storm of social anxiety, isolation, disruption of activities in school, and then a rise in screen time.

JOHN YANG: Are the treatments for males the same as the treatment for females?

Or do you have to come up with new techniques, new approaches?

JASON NAGATA: Well, unfortunately, most of the research has been based on female, not male.

And so we don't have really great guidance.

And in fact, previously, lots of periods with the criteria for anorexia nervosa, and so it's actually been hard to diagnose boys because some of the diagnostic criteria actually don't reflect some of the experiences that they're facing.

One of the first patients that I took care of as a student was a 16-year-old male wrestler, who had actually been struggling for years with an eating disorder before anyone recognized it as an eating disorder.

By the time that we saw him, he was obsessed with his weight.

He was checking his weight 10 times a day.

He was working out for seven hours a day, and he would only eat protein supplements, nothing else.

And so unfortunately, he had gotten to a severely malnourished state and actually had to be hospitalized.

And I remember at the time trying to student, trying to read up about guidelines and how to best help him.

But I think that is all based on female samples.

JOHN YANG: What do you tell parents, guardians or anyone who's got a young male that care about their lives?

What are the signs they should look for?

JASON NAGATA: You know, muscle building goals are pretty common in teenage boys, a third of teenage boys report that they're trying to bulk up or gain weight, and not all of them will develop an eating disorder.

However, warning signs for an eating disorder occur when a boy develops the preoccupation or obsession with food, exercise, appearance or weight in a way that impairs their school or daily functioning, and also starts to really worsen their quality of life.

So for instance, some of the boys have eating disorders that I care for, spend five plus hours in the gym.

And if they aren't in the gym all day, they feel guilty about it.

They won't be able to eat out with family or friends because they perceive restaurant food or home cooked food to be insufficient and protein or more to daddy.

And so when it really gets to a point where it's impairing your social functioning or work, school functioning, that's I think when it borders into a disorder.

JOHN YANG: If parents spot these signs, what should they do to help?

JASON NAGATA: I think a good first step is to talk with your primary care pediatrician who can help to get a referral to an eating disorder specialist, a mental health provider and a nutrition provider that helps support your child.

JOHN YANG: Dr. Jason Nagata of the University of California San Francisco, thank you very much.

JOHN NATAGA: Thank you for having me.