tonight on "nightline," bieber's meltdown. at the end of his rope? tonight, justin bieber loses his cool after being hospitalized. inside the biebs' worst week ever. dream diet. from cheese to pastries. it's all on the menu. the french nutritionist who says you can trim down while eating exactly what you want. deep blue sea. today a so called shark swarm off the east coast of florida. but what's going on beneath the surface? we dive deep into the unknown.

from new york city, this is "nightline" with juju chang. >> tonight, it's a dangerous mix of fame and fortune that can too often lead to reckless excess. plenty of pop stars have cracked under the pressure of celebrity and tabloid scrutiny. now justin bieber is feeling the stress. his week has been marred by hospitalization and a blow-up with the paparazzi. the larger than life 19-year-old is finding out supersized fame comes with supersized baggage. abc's nick watt reports. >> reporter: is this the moment the pint-sized prince of pop finally snaps? >> what did you say? what did you say? >> reporter: bieber exits his london hotel, paparazzi, of course, await. perhaps just a little physical contact. >> what did you say? [ bleep ]. >> reporter: that's a bold statement when you're 5'7" and weigh about as much as my grandma. >> justin bieber is starting to feel the pressure. he's literally having his michael jackson leave me alone

moment. ♪ if i was your boyfriend never let you go ♪ >> reporter: bieber is right now only halfway through a gargantuan ten-month, 125-date world tour. will he make it to the finish line in atlanta in august? thursday night, bieber was breathless onstage. later treated by emts behind the curtain. >> he's backstage with the emts and the doctor. they are telling him that they want him to go see somebody. he has just told me, five minutes, if it's okay with you guys, he's going to come out and finish the show. >> reporter: he soldiered on. then was rushed to the hospital after the show, from where he posted a topless snap on instagram to reassure global believers that their god is still of this world. >> i think what he needs to do,

number one, is get a solid medical diagnosis and figure out what happened and why. and number two, justin and his team need to sit down and look at his schedule, because something's going to have to give on his schedule. >> reporter: after today's unseemly scuffle, biebs tweeted sometimes when people are shoving cameras in your face and yelling the worst things possible at you, well, i'm human. rough week. indeed. yes, indeed. it began last friday. a number of friends, including his rumored squeeze, were denied entry to a club where the biebs was throwing a birthday bash. worst birthday ever, tweeting the mad 19-year-old. monday he was reportedly nearly two hours late onstage. young fans forced to stay up way past their bedtimes. >> it was my9-year-old daughter's birthday present and you've upset her. >> it did ruin the experience quite a lot. i would have liked an apology to sort of say sorry or an explanation. >> reporter: he later

apologized, cited technical problems and claimed he was actually only 40 minutes late. wednesday he launched a ten-minute twitter rant. as long as my family, friends, and fans are with me, you can say whatever. next day, of course, the breathlessness and hospital, and this morning, let's just watch that again. >> what the [ bleep ] did you say? you want to [ bleep ] with me? >> reporter: bieber is no stranger to flipping off flaf s photographers, but is his behavior becoming more erratic since the split from selena gomez? >> he got busted for smoking weed, he's really sorry about it, people make mistakes and he's never going to do it again. >> reporter: he's been caught speeding. mooning fans on twitter. and accused of getting rather too fresh with a young fan, although she claims this was not at all what it seemed. >> when you're that overexposed,

you may experience a backlash. >> reporter: don't forget that just five years ago, justin bieber was an unknown cute little canadian. his mom up loading her wee boy's cover versions on to youtube. that's how he was discovered. five chart-topping albums later, he's worth over $100 million. he's duetting with nicki minaj on his latest album "believe." the kid has 35 million twitter followers. more than any other celebrity. and seems to have no place to hide. a couple of months ago, bieber called 911 to report five cars on his tail. >> they just will not stop following me. >> okay, what's your name? >> justin. >> reporter: a paparazzo was killed recently in l.a. chasing bieber's car and bieber wasn't even in it. >> i think like a lot of young people, justin needs to learn he's not invincible and that he can't work 12 hours a day and then party four hours every

night. >> reporter: today bieber tweeted only way someone can break you is if you let them. is he okay? should we worry about the little fellow? he was back onstage tonight doing whatever it is he does that the youngsters seem to like. ♪ as long as you love me >> reporter: in real life, as in that song, does he just want us to love him. maybe his troubles are just a series of publicity stunts. maybe they're working. i didn't used to give bean ae d moment's thought. now i'm following his every move. >> just 19. our thanks to nick watt. up next, need a diet you can stick to? well this one claims it can help you shed pounds by eating all your favorite things. [ female announcer ] switch to swiffer wetjet, and you'll dump your old mop. but don't worry, he'll find someone else. ♪ who's that lady?

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from co taur uture to cuisi living french means living well, and living thin. so what is it about the french diet that may be helping them stay far slimmer than americans? and if you think they're cutting out wine and cheese, for the french, even dieting is done in style. the french are relentlessly chic. their couture is chic, and their cuisine, oh la la. but despite their love affair with creamy cheese and fine wine and pastries, french women are still skinnier than americans.

sad, but true. french obesity rates have doubled in the past 15 years, but they're still three times lower than ours. and this new book, "the parisian diet", reveals all of the french secrets to staying slim. >> there's so many food possibilities. >> rachel is an american eating like a frenchman, but it wasn't always that way. >> i've done nutrisystem, slim fast, weight watchers, jenny craig, diet center, medifast. >> but you successfully lost weight on those diets. >> yeah, over the years, i've lost 20 pounds, put back 25, lost 30 pounds, put back 35. >> so what makes this diet different? >> because the main thrust of this diet is enjoying your food. and really paying attention. >> but it's working. she says she's lost 11 pounds in five weeks. >> everything fits better. everything looks better. which is really important to me. >> portion control has been the secret to rachel's success.

>> but this is an american portion. i have to whittle it down. >> to a french size. >> to a french size. >> and when we sat down for lunch, that single serving filled a family size bowl. >> that's a super size salad. >> the french people, they enjoy every bite they take in. this is one of the secret keys of the french food. >> dr. jean michelle cohen is the expert behind the french guide to skinny eating. he's also the host of a french tv show in france. dr. cohen says it's not so much a diet, but a new attitude towards food. he showed me the difference at his favorite french restaurant in new york city. so this is the difference between an american sized portion and a french. thank you, pascal. >> the first way is when they eat, they are taught very young that bigger is better. in paris, for example, we prefer

quality, and this is the enjoying aspect of the food. >> his first tip, smaller portions mean fewer calories and nothing is forbidden. even pasta. the french pasta had a tiny amount of sauce, but lots of flavor from fresh herbs and salty olives. the american dish was drenched in creamy sauce. and it's three times the size. tip two, saver your food and avoid mindless eating. i have trouble with this one. half the time i'm grabbing a quick lunch at my desk. and it's cold. it's not even good. no wonder i don't remember what i had for lunch. dr. cohen says those are classic american mistakes. oh, my goodness. instead, he says we need to enjoy the entire experience and linger over a meal. >> but, you know, you need ten minutes to realize if your hunger is cut or not. when you are served with a plate like that, you cannot consider

it because you have your plate and you need to clean your plate. >> his third tip, never deprive yourself. he says it's better to have a smaller portion of something flavorful rather than having a boring salad that gives you no pleasure at all. there's nothing more american than fast-food. but dr. cohen says no food, no matter how rich, is ever totally forbidden. this seems like diet sacrilege, but you actually think a big mac is okay for a meal. >> yeah. but the problem is in reality that you accompany this with french fries and a soda. but you have to take your time and you have to enjoy it. >> but just remember, saver the burger. but try a salad on the side, not fries. and certainly not every day. but honestly, you must be the only nutritionist and diet expert who would say a big mac is good for lunch. >> i know it, but i know perfectly the value of calories of the big mac. it's about 500 calories. >> just ditch the fries. >> yeah. even if they are french. >> dr. cohen says the french

tend to cook more as well, which contributes to healthier eating, but who has time to go home and cook? turns out americans work 10% longer every week than the french, who average 38 hours a week. americans, 42. perhaps that's why americans rely more on prepackaged, processed food. it's no wonder we're a nation that gobbled down lunch and picks up fast-food for the family. >> it's very good. >> maybe we could all use a little more. who's in for a midnight snack? i'm hungry. up next, sharks swarm dangerously close to a florida shore, and another eye-popping close encounter with the mysterious ocean kingdom. you won't believe what you're swimming over. but as time passed, i started to notice max just wasn't himself. and i knew he'd feel better if he lost a little weight. so i switched to purina cat chow healthy weight formula.

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it's what spring breakers fear most. blood in the water as they dodge clusters of hungry sharks migrating north off the east coast of florida. but for thousands of sea creatures living in the ocean deep, steering clear of dangerous waters isn't an option. in this rarely seen underwater menagerie, survival depends on a fascinating and beautiful array of adaptations. tonya rivero dives in. >> reporter: off the coast of florida, thousands of spinner sharks migrating north and close to shore have closed beaches and frightened vacationers. the ocean is most on display when it makes us afraid.

but what happens near the shore is only a sideshow. with 3/4 of our planet under water, the main attraction lies beneath the surface. >> the diversity of life in the oceans is staggering. there are whole groups of organisms that have no counterparts on land. >> reporter: a world where courtship and mate iing, but especially avoiding death plays out against an often alien landscape. >> millions and millions of years, animals and plants evolved in the ocean, and only relatively recently came out on land. that's why there are so many more different kinds of creatures in the ocean than there are on land. >> reporter: but the eternal dance between the hunter and the hunted is for all its brutality balanced. creatures on the lower end of the food chain have developed astounding ways to protect themselves. the simple jellyfish with its stinging cells thrives, and the

blanket octopus can actually detach one of its lovely limbs as a decoy. and of course, there's always the ink. and the aptly named spanish dancer is a sea slug who can fly. a lion fish has venomous spines, and some her met crabs attach poisonous athemnies to their shells. take the sea dragon and the stone fish. many also use their camouflage to ambush their own meals. but sometimes something larger is the answer. >> if you think about the open ocean, there's not a lot of places to hide. so one of the best places to hide is near something big. preferably something big with teeth. >> reporter: but even evolved defenses don't always work.

this enormous school of lantern fish does nothing to stop the spinner dolphins who push them to the surface where there is no escape. krill also seek refuge by forming a dense ball, which makes it harder for small fish to find a target, but allows the blue whale to gorge. >> they can't escape from the blue whale, which evolved to eat them. scientist call it the evolutionary arms race. because the prey have got to come up with solutions but the predators have to keep up. >> reporter: part of the species' ability to survive is its reproductive prowess. the asian sheep may have a mug only a mother could love, but his mating dance is still a success. once a year, spider crabs molt and mate in a massive orgyastic pile. and for dolphins, sex is just part of being friendly. amazingly, many coral reproduce

just once a year, always at night just after the full moon. an entire reef unlish unleashes blizzard of sperm and egg that unite to form new reeves that can expand hundreds of miles, and so it goes and grows. >> we're just beginning to understand how life works in the ocean. we haven't even begun to scratch the surface. >> reporter: why why should we care about the teaches of the deep? it is simply in our best interest. >> so many economies are absolutely dependent on healthy oceans. 15% of the world's protein comes from fish produced by the oceans. that's a nontrivial amount of food. if you care about living creatures, the wonder and magic and beauty of the oceans are something that you should care about. >> reporter: this kingdom of the oceans is ultimately our world.

i'm tonya rivero for "nightline" in new york. >> fascinating. who knew sea creatures were so frisky? "kingdom of the oceans" premieres march 10th on nat geowild. it's time for this week's closing arguments. this week, north korea threatening to strike the u.s. and turn washington into a sea of fire. the new leader kim jong un vowing to break his country's peace pact with south korea. and missile tests from pyongyang prompting new u.n. sanctions. so what do you think? as tensions rise in the region, should the u.s. respond to north korean provocations, or not? weigh in on the "nightline" facebook page or tweet us @nightline. thanks for watching abc news. we hope you check in on "good morning america." they'll have the latest on the winter storm battering the northeast. and a controversial new tsa decision that allows passengers to carry knives onboard. gma is working while you're sleeping and we're always online at abcnews.com. have a great weekend.

see you back here monday. ñtút!tp