this is "nightline." >> tonight -- bulking up. this young man went from skinny to super buff with extreme workouts and food plans. but when does the obsession with muscles cross the line to compulsion? >> it would have been succumb to death at an early age by pushing myself beyond what my body was capable of. plus an olympic fencer whose unconventional training is for mental toughness. everything from ice baths to confronting bears. >> i literally looked it in the eyes. we're going to do this. so if i can do that i can do anything. >> all for the glory of the gold. and break out the ears and whiskers. we've got a new memory for her.

"cats." but first, the "nightline" 5.

cc good evening. thanks for joining us. tonight the two men you're about to meet set about chasing an image of muscular perfection,

dramatically pushing their bodies to bulk up. but for one of these men the obsession went way too far. here's abc's gio benitez. >> reporter: washboard abs. chiseled pecs. nearly 200 pounds of pure muscle. >> what's your height? >> 6'2". >> weight? >> 192. >> body fat? >> probably like 12, 13. >> i 18-year-olds don't know about themselves. >> i'd say so, yeah. >> reporter: at just 18 years old, david late is often seen as the poster boy for physical perfection. but just four years ago david looked like this. just 98 pounds at 14 years old. he says he was bullied in school for being scrawny. >> every aspect of my life was basically just heavily impaired by like how insecure i was and

videos for advice on how to transform his body. >> i just went on youtube and i typed in chest workout. >> reporter: now he's a social media celebrity himself. this transformation video chronicling his weight gaining odyssey has more than 14 million v views on youtube. what do you think it is about that video that had so many people looking at this? >> i think it's the completely massive change in the human being because i was just like a small skinny kid sudden it's a completely massive transformation. >> reporter: he lifts big, sometimes up to six hours a day. and eats nearly 5,000 calories. >> doesn't have to know about these. >> reporter: posting it all on social nemedia. >> you think people are looking for before and after? >> before and afters. people think if he was just an average person, he looked lake this and he ended up achieving this type of success, that motivates you.

when i would see transformations like that it would be crazy inspirational. >> reporter: you can call what he does bigspiration. today videos p men like david flexing and pumping iron have millions of views giving a new crop of scrawny boys advice on how to get bigger faster. but for some the desire to bulk up can just as easily be an obsession, leading some young men down a destructive path, compulsively dieting and working out, never feeling quite big enough. >> ideal male body size kind of more and more inflated over the years to the point where it would be very difficult for anybody to kind of achieve this. >> here i am around 20 and at 140 pounds, and then on the ride here i am around 25, 26, 260 pounds. >> reporter: for 29-year-old web designer dylan haffertepen the question for maximum muscle has been a lifelong struggle.

beat myself up because this is so out of reach and why am i not there? >> reporter: at 18 the california native weighed 140 pounds. but in seven years he doubled his size, following intense workouts, drinking six protein shakes a day, and spending half of his paycheck on supplements. >> a couple of proacid. acetone choline. honestly i should scale back. some of them i keep taking out of habit. >> reporter: his >> i would always choose to work out over hanging out with friends. i would not go out to eat. i had my meals prepared and i would eat them all by myself. i usually picked jobs where offices were near a gym of my preference. i was so caught up in that lifestyle, obsessed with getting bigger, bigger, bigger, that i never really considered this a problem. >> reporter: despite getting up

never felt big enough. >> i perceived myself as very small and weak and inadequate. i would get very upset about how small my arms seemed in proportion to my waist, to my shoulders, to my neck. i would focus on all these things that made me very upset. >> reporter: dylan says that bodybuilding videos on social media were a trigger for him. >> you don't see any average-looking superheroes, and that can create this false idea of what the male pqu be. >> reporter: his infatuation with getting huge ultimately landed him in the hospital. he had gotten so big his blood pressure was so high he had to have his heart shocked back to normal. >> i had negotiated with myself that, you know, it would have been okay to succumb to death at an early age by pushing myself beyond what my body was capable of. there's no amount of size i could have added in that

needed help. his quest for the perfect muscular body was actually a psychological condition known as muscle dysmorphia, more commonly called biggerexia. >> people with muscle dysmorphia have a belief or a perception that their body is too small or scrawny, that they're not muscular enough. and they have a very strong desire to become bigger. >> reporter: roughly 1 in 50 people in the affects just as many men as women. up to a quarter of those people are believed to be muscle dysmorphic, which is sometimes called the reverse anorexia. >> people are anorexia nervosa believe they're too fat or too large and they want to become thinner where as people with bigorexia believe they're too small and not muscular enough and want to become bigger. >> reporter: patients are most often treated with medication specific to their symptoms and therapy that targets damaging

amount of time that they're, say, checking in the mirror, which helps them think less about their appearance, gradually cut down the amount of time they're in the gym, help them deal with the fears that they have, that they're going to possibly lose muscle mass or lose size if they exercise less. help them reframe their ideas about the importance of appearance in general. >> you can be a bodybuilder. you can be a fitness nut. and that's great. but when is that disorder that is endangering you? that's when you need to look for help. >> reporter: bodybuilding videos on social media were a trigger for dylan, but there's no evidence they cause muscle dysmorphia. and people who work out, even hardcore devotees like david, don't necessarily have a problem. >> your body has changed dramatically. now you're thinking you still want to get bigger, you still want to get stronger. >> yes. i would like to increase my muscle mass, increase my

the gym and training consistently. but i'm by no means like ridiculously obsessed with it where it's taking over my life. it's just something i enjoy doing. like that's just what i do. >> reporter: but for people like dylan, struggling with their perception of their own body, after three years of therapy he says he's stronger now inside and out. >> i have a greater appreciation for myself. i can now look in the mirror and i am not hung up on these i'm not obsessed with focusing on flaws, how skinny i am, how weak i am. i see beautiful dylan. >> reporter: for "nightline" i'm gio benitez in new york. up next, the olympic fencer who believes his mental training will give him the ultimate edge in rio. and later, from "bleeding love" to "memory."

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cc1 test message cc1 test message you know, when you're an olympian, at the peak of your sport, it's tough to find a competitive edge. tonight we find one athlete who's going to extremes in hopes of gaining just that, at a camp that uses some highly unorthodox methods to train elite athletes how to perform under do or die

? miles chamley-watson is going for gold in rio. at 26 he's the platinum blond, tatted-up world champion fencer who happens to moonlight as a high fashion model. >> for the olympics it's the most high pressure situation. it's every four years. you want it so bad. and it's just likyo >> reporter: training up to seven hours a day. he's been dreaming of olympic gold since he was 10. >> i first tried fencing just for fun. it was offered in gym class. i fell in love with it right away. and when you start to win you kind of start to really see a little angle. >> see what you can get out of this. see what you can get out. >> reporter: and just weeks before the most crucial competition of his life, miles is taking an unconventional approach.

he's training his mind as well as his body. >> to be able to control your emotions is probably the most important thing for any person in general. an athlete is probably the most important. >> reporter: welcome to red bull's performing under pressure camp. here in the epic landscape of montana, nine extreme athletes from a rock climber to a big wave surfer coming together to gain that extra edge on their opponents. >> so how will this help you going into the olympics? >> this is so much bishl to me than just benifencir going to the gym. you can't buy these experiences. >> oh, my god. >> reporter: one of the biggest lessons, facing down your fears. >> look at mielsz. >> reporter: even if it means coming face to face with a 1,000-pound grizzly bear named bart. >> what went through your mind when you saw that bear? >> if i could outrun that bear. if i can do that i can do anything. >> you can face down anybody with a -- >> foil?

conquered the bear. the real bear is the fear within you. >> reporter: miles is also training to push through the pain and payne of high pressure scenarios. learning enhanced breathing techniques pioneered by world-renowned ice man wim hoff. >> i always say i don't care how good you are, i'll make you better. >> reporter: these exercises in keeping cool under pressure preparing them for freezing cold ice baths. >> you keep on going with the breathing. and we go all for five minutes. fully emerged up to here into the ice water. it's a big impact on your chemistry, but you are in control! >> my hand is starting to hurt. it's been a matter of seconds. >> absolutely.

the deep breathing seems to be helping him ignore the pain signals. >> ease down on the breathing. ease down in the breathing. keep on breathing! don't catch. keep on breathing. who's the master? >> control of the mind is letting go. >> this is beyond. >> reporter: he somehow manages to stay submerged for ten long minutes. >> come on. >> i think it's so important to really focus because if i didn't focus on my breathing i would have never been able to stay under the water -- stay in that thing for ten minutes. no way. >> yeah. because you were struggling that first time you went in. >> yeah. it sucked. >> it's painful. >> reporter: and yet during competition the biggest enemy may be emotions. just hours before his olympic debut in london four years ago miles says he was caught off guard by a phone call from his estranged dad. >> i picked it up and he's like

>> reporter: he says his angry reaction cost him a medal, placing fourth. >> i was number one in the world that year and i couldn't even focus at pull. i trained my whole life for this and i let something like that ruin it. >> reporter: which is why this touchy-feely part of the training camp may help miles the most. training the athletes to get in touch with their emotions. >> come on, come on. cry. >> reporter: coached by professional actors from cirque du soleil, miles ias life. use that as a marker. acting. you're not being judged on it. yes, yes, yes, yes. >> honestly, i haven't cried since i was literally 11. >> reporter: years of pent-up resentment and pain spilling out on stage. >> something got you there. what was it? >> i guess i thought about my dad maybe growing up. i was like not only crying but okay like he was -- let it all out. you know, it's like real men cry. >> you were crying for the 12-year-old boy. >> i just block it out.

make you cry, like okay -- >> you got there. >> yeah. quick. super quick. >> reporter: by moving beyond his hurt, miles hopes this time around he'll be in full control of his emotions as he enters the olympic arena once again. if we see you up on that podium in rio, how much of a role would this camp have played? >> a lot. huge role? >> really? >> yeah. i'm a step ahead of people i think normally but now this is a whole other >> this is like trying to unlock the secret sauce, isn't it? >> it is. because everyone has it inside of them but no one really knows how to attack that. >> i've attacked you. to create a legacy, not a moment. what will you be remembered as? next, after a 16-year cat nap a beloved show returns to broadway.

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the musical "cats" inspired a generation to sing and dance and possibly back pet owners. now the show returns to entertain a new generation. our ginger zee joins the cast. >> reporter: let the memory live again. "cats" is back. the legendary musical was once broadway's longest-running show. and now a new day has begun at the neil ? this fierce feline reincarnation bursts with the beloved music and dances that millions remember and adds a new voice front and center. pop star leona lewis. ? keep bleeding ? ? keep, keep bleeding ? who's gone from bleeding love -- ? touch me ? to "memory." one of broadway's most unforgettable songs. it's something you that saw as a child? >> i did. it was so magical. it blew me away.

cat-inspired choreography is there but updated by andy blankenbueller. >> you did "hamilton." now you're doing "cats." >> "cats" is very similar to "hamilton" in that music never stops and "cats" was a revolutionary show when it opened and it really changed how people viewed theater. so in that regard i think the projects are a little parallel. >> reporter: the set is part junkyard, part playground. >> it is really like a tire. >> yeah. it's pretty slippery here. >> reporten like a cat. you have to dance like one. >> it's as if that moon hits you in a crazy way and just paralyzes you. >> we're going to go ahead and speed up that half hour it took to learn the routine. >> i can't just dance like a cat. i have to look like a cat. >> reporter: a mere one hour later -- >> i'm feeling so much more feline. rah. >> five, six, seven, eight. >> reporter: and then no pressure, but the full cast

i dance. i prance. i strut. i hold my own. for fans of this iconic musical their days in the sun are still going strong. >> that ginger zee moves like a cat. thanks to our chief meteorologist for that. and dancer. "cats" is now on broadway. check it out. thanks for watching abc news. join us for "good morning am and as always, we're online at abcnews.com. and our "nightline" facebook page. good night, test. >> announcer: today on the meredith vieira show and the new tweet that has donald trump in hot water. and could this damage trump's reputation. and the first grader getting suspended from school for three days.

>> is that up. >> no. >> it all starts right now on "meredith". ? >> we have a great show today. yes, we do. the show the left overs. that is good. and she stars in the left over. and regina king is here. [applause] and she had an incredible career and now taken home an emmy in september. and see richly deserved and gave such a great speech.