i'm only one call away i'm only one call away this is "nightline." >> tonight -- >> a lot of folks in the media would love to see donald and me get in a giant food fight. >> from dinner party to the hunger games. >> not a lot of conservatives come out of manhattan. >> less than three weeks to go before the iowa caucus -- >> that was a very insulting statement. >> the gop's finest serving up fresh insults. >> at least half of the things marco said are flat-out false. >> and just deserts at tonight's republican debate. fit to fat to fit again. one trainer so committed he's

risked it all, packing on the pounds. >> oh, that is -- >> to then boomerang and drop that weight along with his clients. >> if i haven't lost weight, i'm going to be piss the. >> a whole new gist on the highs and lows. is this ultimate yo-yo diet safe? >> prove to me that i didn't waste four months of my life. i'm your lady and he was her husband and mentor. transforming celine dion from a teenager with dreams into an icon. with early hits like "the power of love." the power of love >> celine's heartbreak over the passing of rene angelil. first the "nightline 5." >> enough pressure for you? too late, we're about to take off. >> it works fast, liquigels. >> you're coming with me. >> i'm gold status! >> dissolves fast to unletter max strength medicine. let's end this. when cigarette cravings hit

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good evening. we're weeks away from the caucus showdown in iowa and the claws came out tonight at the gop debate. manners taking a back seat as candidates slam democrats, attack each other, all fighting for the heart and soul of the republican party. who scored big? here's abc's david wright. >> reporter: tonight donald trump was center stage in every way. accusing his nearest rival ted cruz of being too canadian. >> there's a big question mark on your head. and you can't do that to the party. you really can't. >> reporter: cruz hit back hard.

>> the constitution hasn't changed. but the poll numbers have. and i recognize -- i recognize that donald is displayed that his poll numbers are falling in iowa. >> reporter: now that iowa is less than three weeks away, the gop debate no longer seemed just politely contentious. >> i have a feeling -- >> reporter: like the lead-up to a rose ceremony on "the bachelor." >> i'm probably going home. >> reporter: now it's more like "the hunger games." kill or be killed. ahead of this debate cruz swore it wouldn't come to this. >> a lot of folk in the media would love to see donald and me get in a giant food fight. i'm not going to engage in that, i hope donald won't either. >> reporter: but there he was accusing trump of having new york values.

>> everyone understands that the values in new york city are socially liberal, pro-abortion, pro-gay marriage, focus around money and the media. not a lot of conservatives come out of manhattan. i'm just saying. >> conservatives actually do come out of manhattan, including william f. buckley and others, just so you understand. and just so -- if i could, because he insulted a lot of people -- >> reporter: trump accused cruz of being a canadian. on the campaign trail trump has been goading cruz about whether cruz, who was born in canada, is president. >> he was actually a citizen of canada until 15 months ago, understand. and that's a big problem. >> reporter: cruz was born in calgary, alberta, to a cuban father and american mother but renounced his canadian citizenship in 2014. he insists he's american through and through.

that's why they're voting for you. >> reporter: this new endorsement ad from "the duck dynasty" patriarch. >> our qualifications for president of the united states, is he or she godly? does he or she love us? can he or she do the job? finally, would they kill a duck and put him in a pot and make a good duck gumbo? ted cruz is my man. he fits the bill. >> reporter: town halls in iowa, cruz has dismissed the citizenship controversy as a sideshow. >> i have never breathed a breath of air on this planet when i was not a u.s. citizen. >> i choose him as my vice president presidenttial candidate and the take him along for the ride? i don't like that, okay? a moment ago offered me the vp slot. i'll tell you what. if this all works out i'm happy to consider naming you as vp. >> reporter: tonight cruz also took fire on this story, the

"new york times" breaking cruz and his wife failed to disclose massive loans to his senate campaign from goldman sachs and citibank. even as cruz has railed against wall street out on the stump. >> the federal government has bailed out wall street but somehow seems to abandon main street. >> reporter: cruz dismissed the "times" story as a smear. >> yes, i made a paperwork error, disclosing it on one piece of paper instead of the other. >> reporter: jeb bush, who once stood toe to toe with trump, tonight urged him to consider changing his mind on banning muslim immigrants. >> i hope you reconsider this. because this policy is a policy that makes it impossible to build the coalition necessary to take out isis. >> reporter: bush is still among the best-funded candidates, raising millions from the bush political machine. but support from republican insiders hasn't translated to support in the polls. tonight trump seemed to take special pleasure in smacking bush down. >> we don't need a weak person being president of the united

states, okay? because that's what we'd get if it were jeb. that. we don't need that. >> reporter: his supporters love that about him. the way he takes on anyone who stands in his way. >> trump! >> do i agree with what trump i certainly do. >> reporter: trump's supporters delighted this week when he attacked the technicians who did the sound system at his rally. mike. whoever the hell brought this mike system don't [ bleep ] put it in, i tell you. >> reporter: tonight that trump candor again on full display. >> your comments about banning muslims from entering the country created a firestorm. is there anything you've heard that makes you want to rethink this position? >> no. >> reporter: you might think that the democrats watching from home are enjoying all this. but they're too busy managing their own food fight. the latest polls have bernie sanders pulling even with hillary clinton in iowa, pulling

so the clintons are now in full attack mode. not just hillary and bill but chelsea too, attacking sanders on health care. >> senator sanders wants to dismantle obamacare, dismantle the c.h.i.p. program, dismantle medicare, dismantle private insurance -- >> reporter: the sanders campaign outraged saying his plan would do nothing of the sort. >> that is factually incorrect and i hope the clinton campaign stops saying that. >> bernie sanders is now running a very strong campaign. it looks as though it's going to be a very competitive race until the bitter end. >> reporter: the democrats have their next debate sunday. it will likely be every bit as contentious as this republican one was. >> i appreciate your dumping your research folder on the debate stage -- >> it's your record. >> i will say at least half of the things marco said are flat-out false. >> reporter: the question is did it move the needle for any of the candidates? >> donald trump is very happy with his performance tonight. ted cruz may have some questions.

and looking forward to new hampshire, i think christie and rubio are happy with their performances tonight. >> reporter: we'll know soon enough. public 1st february 1st iowa voters will either prove the pollsters wrong or wear them out. david wright for "nightline" in new york. up next, one weight loss trainer taking empathy to a whole new level. we've never seen a weight loss diet quite like this but is it safe? later, because you loved me and the many timeless ballads taking on new meaning as celine dion mourns her husband's death. 's where your friends are. seriously, it's, it's really fine. you don't want to be seen with your dad? no, it's..no.. this about a boy? dad! stop, please. o, there's tracy. [ horn honks ] what! [ beeps, tires screech ] bye dad! it brakes when you don't. forward collision warning and autonomous emergency braking. available on the newly

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a master class in yo-yo dieting. imagine dedicating your entire life to fitness and throwing it all away to help someone else. here's abc's nick watt. ray. >> good to meet you, ray. >> reporter: fit to fat to fit is a weight loss tv show with a big fat twist. j.j. the trainer had to gain weight, a lot of weight, before helping ray try to lose it. >> i have something to tell you. i'm going to be gaining 60 pounds from where i am right now so that i can better understand and relate to where you're coming from. >> we both wear our emotions on our sleeves. >> cry a lot. >> it's going to be an hour of two men sobbing. >> in one aspect it breaks my heart you're doing that to yourself. part of me is just sad for you. because i know what it's like. it sucks. i don't want anyone else to go

there. >> i'm sick. you seriously might need to get a garbage can. >> you gained 65 pounds? >> 184 to 245. >> that is awesome. >> 61 pound in the space of? >> 120 days, 16 weeks. >> that cannot be good for you. >> no. no it's not recommended. >> what are you doing? >> just trying not to die. >> it's the hardest thing i have ever done in my life. i was not prepared for what it did to me mentally, emotionally. it wrecked me in every way. >> too much rice. >> you're kind of turning into a complainer. >> reporter: j.j.'s wife erika is a nutritionist. >> was he a bit of a nightmare? >> yeah, a big nightmare. let's just say he was way worse than i am ever, pregnant. >> reporter: j.j. was closely monitored by doctors. >> increase toll goes off the charts, triglycerides are up, you become pre-diabetic, medically obese. >> reporter: this doesn't come without risk.

>> there's very limited data on the deliberate weight gain and then weight loss of healthy individuals. even if it's temporary over a long period of time, we don't know what the cumulative effects of that would be. >> rise and shine. >> nuh-uh. i'm going to sleep until dinner. >> it felt like he was a totally different person. i didn't feel like he was my husband anymore. >> when i watched it i was thinking, what this is guy doing this to himself? >> because he's nuts. >> i get a small glimpse and a new perspective as to the struggles that come from that place that you are in before you start that weight loss process. >> you finally understand what it's like to be the fat guy? >> i was in a very, very dark place for most of that 120 days. >> how are you doing, man? >> i'm doing good. >> four months ago j.j., he was frickin' ripped. j.j. is in the pudgy boy's club. >> reporter: then they both beat the bulge together.

>> thanks, brother. >> start off killing it. >> i didn't go through four months of hell to have you give up on me. prove i didn't waste four months of my life. find your breath, find your rhythm. you got it. four months ago, this was so easy. today i feel like i'm dying. >> reporter: now ray's motivation, apart from j.j. and the tv cameras, is a big one. >> my wife and i are hoping to adopt. i don't think someone's going to place a kid with us at 400 pounds. you know? i want to be that dad who goes out and goes hiking with his kids. i want my children to be in awe of the man i am. like i am in awe of the man my dad is. and i'm not going to do that at 389 pounds. >> reporter: with basically a food addiction. >> you think most of this was just what ray was putting into his body?

>> all the cliches are true. it's hard work and exercise. and you cannot outwork a bad diet. >> reporter: with this, a bit of this, a lot of this -- >> start off killing it. >> reporter: not too much of this, ray lost a whopping 147 pounds in just five months. >> make no mistake about it, the cardiovascular system can be impacted on dramatic weight gain or weight loss. some of those impacts might be positive, some might be negative. >> oh my god. 242, are you freaking kidding me? yeah, yeah! oh my gosh, yeah! >> you lost a decent-sized human being. >> that's right. >> you lost you. >> yeah. >> reporter: again, that much, that fast, can be dangerous. again, doctors monitored ray the whole way. >> ray's wife julie also lost 75 pounds doing the exercises j.j.

gave to ray and the food plans from his wife erika. >> the plan was not for you to lose weight as well? >> we live together. it's our lifestyle. so it wasn't difficult to jump on board. >> reporter: their entire lifestyle now totally changed. >> instead of just sitting around watching tv at the end of the night, we'll challenge each other to a max blank contest. >> pushup position but on your elbows. see how long you can stay up. >> this is what you do for kick in the evenings? >> sometimes, yeah. >> reporter: j.j. is now back to his fighting weight of a little over 190 pounds. and has his identity back. your identity is the buff guy. >> that was my identity. now i feel like i am so much more than just the buff guy. right? i feel like i'm more well-rounded and i come from a place of love rather than a place of judgment. >> haven't you done yourself lasting damage? >> oh, man, i don't know.

besides the few stretch marks i have on my hips, that's the only thing that i'm still carrying from this little adventure. >> you wear them with pride? >> i wear them with pride, i love those stretch marks. >> reporter: ray and julie are now all signed up hoping to adopt a kid any day now. five months. >> don't think i don't know that. >> reporter: filming finished in october. ray has not let himself go. he has, in fact, lost even more weight. >> i'm that like 13-year-old high schooler, flexing in the mirror after a shower. >> reporter: on the day we visit for the first time in his life ray climbed a rope. >> that's what i'm talking about right there, dude, whoo! >> reporter: i'm nick watt for "nightline" in salt lake city. >> "fit to fat to fit" premieres tuesday and a&e, owned in part by our parent company disney. the voice behind iconic hits like "my heart will go on."

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he was an old school impresario, transforming a teen with dreams into a music legend. then marrying her. tonight celine dion mourns the passing of her husband, mentor, and manager, rene angelil. >> reporter: millions of people in the world that don't even

and you know what? i'm amazed how fortunate we are. >> reporter: her voice providing the soundtrack to love. "my heart will go on" from "the titanic." my heart will go on and on >> reporter: he, rene angelil, was celine dion's real-life epic romance. today the man behind the music has passed away at the age of 73 after a long bout with throat cancer. they met when celine was 12 years old. he a music manager, plucking her from poverty. together they built her career and eventually a relationship. they married in 1994 and had three children together. i went backstage in vegas with the family back in 2011. then rene had already dealt with his first bout of throat cancer. but as she told abc's deborah roberts the disease would soon return. >> he said, i have cancer again, the doctor just called me. my heart started to beat faster

it took a toll on me. >> reporter: that toll and her willingness to bear it a true testament to their incredible love. >> he's got a feeding tube. i have to feed him three times a day. and unfortunately i had to say, listen, i can't be half here and half there. please allow me to stay home. >> reporter: celine says it was rene himself encouraging her to go back to the stage. >> sometimes, and i think i'm used to it, you don't feel what you need to feel. just do it. >> go onstage? >> i did. because i love him. and i did. and -- it was very hard. we complete each other, we're one. >> reporter: now those iconic ballads like "because you loved me" will undoubtedly take on new meaning for the singer. poignant and bittersweet, laced with the memory of the love that inspired them. because you loved me

>> our thoughts are with his family tonight. we also want to mark the passing of an acting great, alan rickman died today at age 69. with his distinctive voice and chilling scowl he played a really good bad guy. a london stage actor so memorably mean on the big screen in "die hard" as the notorious german terrorist hans gruber, he won our hearts and broke them as the cheating husband in "love, actually." ultimately defined his legacy as the dour possessions professor severis snape in "harry potter." the arts community mourning his passing, a man who showed us heroes can hide in the most unlikely of places. thanks for watching abc news. "world news now" is coming up with overnight breaking news. tune into "good morning america" tomorrow. as always, we're online at abcnews.com. good night, am >> hey, everybody. you' re invited to sit back and watch as our players today are faced with some of the most important decisions of their lives. 14 questions,