tonight on "nightline," sugar smackdown. the latest targets in the war on obesity. super-sized sodas and giant juices. as new york city's mayor proposes a controversial new ban on sugary drinks over 16 ounces. could your town be next? and the sweet sound of a child's giggle. it could be a sign of a rare brain disease that's no laughing matter. tonight, meet the doctors racing to find a life-saving cure without a single stitch. plus, he produces everyone from nicki minaj to justin bieber. and just can't get enough hit

so songs himself, as a member of the black eyed peas. we hang for a day with will.i.am. >> announcer: from the global resources of abc news, with terry moran, cynthia mcfadden and bill weir in new york city, this is "nightline," june 1st, 2012. >> good evening, i'm cynthia mcfadden. tonight, are those super-sized drinks really responsible for the escalating obesity epidemic? new york city's major michael bloomberg seems to think at least in part they are. this week, he proposed a city-wide ban on sodas and juleses over 16 ounces. and while those sweet drinks do contain a shocking amount of sugar, many opponents are drawing a battle line between big government and big soda. abc's john donvan takes us inside the sugar war. >> hey, mayor mccheese. >> reporter: mayor mccheese

versus mayor bloomberg. yeah, that's what we had today. mccheese, of course, the one-time official of mcdonald land in those old tv commercials. bloomberg, of course, the real-time mayor of new york city. where the city has just proposed a law that will bar restaurants and other food service businesses from selling soft drinks in cups that are larger than 16 ounces. >> all we're doing here is saying, if you want to order 32 ounces of soda, in a restaurant, that we supervise, they must give you two 16 ounce glasses. and what's likely to happen is, you'll drink one and not the other. >> reporter: to which mcdonald's today actually volleyed back on twitter. mike bloomberg, we trust our customers to make choices that are best for them. wow. jums as the tobacco industry hated it when smokers were forced outside of restaurants and detroit hated it when laws mandated seat belts, the restaurant industry hates this new regulation designed to promote health and like the others is making the freedom

argument. and their response? not that it's smart to be served so many calories, but that it should be your right. >> this is the most ridiculous sort of nanny state-ism. it's none of the mayor's business. obesity is not a public health problem. obesity is a private health problem. >> reporter: the new rules, which could take effect next march, would ban cups larger than 16 ounces of any lick wild that contains more than 50 calories. diet sodas, fruit is snacks and milk-based beverages, even milkshakes, would be exempt from the rule. really, the target is less on soda in itself than it is on the sugar that is in the soda. it's been talked about plenty these past few years. but few have had more to sail about it than dr. robert lustig, who became a micro-celebrity of the sugar wars. you sort of see the nutritional e give leapt of opium dens? >> kind of. >> reporter: some of the numbers

here. a 64 ounce soda typically has the equivalent of 87 sugar cubes. a 32 ounce soda, 61 sugar cubes. 16 ounces of soda, 20 sugar cubes. lustig specializes in childhood obesity. he believes what is making kids fat is something in sugar, a molecule. it's called fructose. a comment ingredient in sodas. it's found in a lot of foods. as is sugar in general. there's sugar in an orange, an apple. at some point, sugar is good for us. >> do you need sugar to live? is it necessary? is there any, even one reaction in your body that actually requires fructose? zero. >> reporter: one of his ideas, to deal with kids drinking in the sugar that's in soda goes a lot further than new york's big

cup ban. >> show me your i.d. 15-year-old walks into a convenience store. wants to buy a can of coke. cashier says -- >> reporter: you want to card kids for coke? >> absolutely. if a parent wants their kid to have a coke, let them buy it. >> reporter: this drink is rated r? >> yeah. >> reporter: he believes all sugars can be harmful. not just fructose, but also simple sugars from fruit. >> you see kids with juice boxes, running around in the playground. >> that's a disaster. makes no difference if it's a juice box or a soda. in terms of the fructose load. >> reporter: he says the level of obese tie in america began to climb around the time the food industry started using lots of high fructose corn syrup. because it's just so cheap and available, and therefore, so everywhere. >> i went to our local supermarket here in san francisco and i checked out 32 brands of commercially available bread on the shelves. 31 of them had high fructose corn syrup. >> every time we focus on one

aspect of the diet, said, ah-ha, that must be what's causing obesity, we've been wrong. >> reporter: this man con adults for the con refiners industry. >> in fact, there's evidence to suggest that it is our own habits, the overconsumption of calories from all sorlss which has led to the obesity epidemic in both children and adults. >> reporter: no one denies there is an epidemic, especially not in new york, where more than half of all adults are obese or overweight. and where the prescription, the mayor's come up with, is clearly not a spoonful of sugar. i'm john donvan for "nightline" in washington. >> it surely is not. our thanks to john dan von. and just ahead, a dangerous disease that has children fighting for their lives. and the main symptom is the giggle. down here, folks measure commitment by what's getting done.

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>> announcer: "nightline" continues from new york city with cynthia mcfadden. >> for the parents you're about to meet, the sound of their child's laughter is an alarm bell, filling them with dread and fear, because their giggle fits are actually the uncontrollable symptoms of a very rare brain disease. tonight, a few doctors with a revolutionary treatment are determined to change that. here is abc's deborah roberts. >> reporter: adorable. priceless. for any parent, it's a treasured and joyous sound. their child's laughter. but for a rare number of children, laughter can signal a heartbreaking future. >> the giggling when he was young was such an endearing type of a giggle. until we realized he was giggling at inappropriate times.

>> reporter: 9-year-old keagan's parents say the mysterious giggle began when he was just a toddler. you thought what? >> he's enjoying himself. >> what's wrong with giggling? >> reporter: something was wrong. a neurologist said his bizarre laughter wasn't funny at all, but potentially dangerous. he was having seizures. >> i couldn't understand how they could call these seizures. he's not convulsing. he's not on the floor like everybody thinks of a seizure. >> reporter: keagan was diagnose noelsed with a form of epilepsy. he's not alone. in toronto, 7-year-old mateo is hit by landing seizures up to six times a day. mri scans reveal the cause for both boys. a small non-cancerous lesion buried deep inside their brains. >> no, don't do that. >> reporter: now, for two families, it's a race against time to find a cure. because untreated, the latching

seizures can cause long-term brain damage. for years, the only hope was invasive high-risk brain surgery, where the skull is open and the lesion removed. at texas children's hospital, dr. angus wilfong has developed a dramatic new way to cure epilepsy, without a drop of blood or a single stitch. so, this tiny, tiny little plastic straw goes right through the top of his head. >> yes. it gets guided through the brain tissue and into this lesion. >> reporter: a laser beam to destroy the lesion and those dangerous giggles. so, now mateo and his parents karen and paolo have come to houston for this new surgery, hoping for a miracle. to help her scared little boy understand how his life is about to change, karen givens him a yoda, with a light saber. >> we talked about the light? all in the laser. >> are you going to shine it? >> going to shine a light on it and it's going to stop making

your seizures. >> reporter: mateo is taken to the mri. time to go to sleep. >> super good, baby. >> reporter: and say good-bye. moments later, doctors carefully attach a frame around his head to begin his mri. for hours they scan his brain, using the cage around his head as a reference, to pinpoint their exact trajectory to the lesion. >> i don't think we have to go any further than this. >> no, i don't want to. >> reporter: if doctors miscalculate, he could hemorrhage or wake up with brain damage. from the mri, he's wheeled to the operating room. >> any concerns? >> no. >> we all agree? >> reporter: it's go time. ma day yoep's head is secured in place. following computer cord nates, dr. curry adjusts and aligns his frame. and like a carpenter in a wood shop, begins drilling a tiny hole, the size of a pencil, into mateo's skull. a laser is inserted down to the lesion.

but are they in the right place? mateo winds his way back into the mri. >> it's hard to believe that this is brain surgery. >> that's right. >> reporter: in real time, doctors discover they are right on target. the cord connected to the 7-year-old's skull is hooked up to a laser machine. then, fire it up. that orange glow, heat, destroying mateo's lesion. >> we're finished. his epilepsy's gone. it's emotional. i'm choked up. and it's going to be a special molt moment. >> you got it? >> it's done. >> he's okay? >> uh-huh. everything went perfect. >> reporter: a lifetime of misery is just erased in a minute. >> yeah. >> reporter: and dr. curry admits he had help from a friend. >> i think he's how i got there. clearly the force. what a relief.

>> cannot even describe how happy i am. >> you're really happy? >> i'm so happy. >> reporter: today, two months later, the strange case of gigfuling solved. that's a real laugh. keegan, the first epilepsy patient with the rare disorder treated by laser surgery, is also seizure-free. >> robin and i were in the kitchen and we hear this laughter and we just kind of tensed up and froze and we walked around into the living room and he was laughing, like, really laughing at the tv show and at appropriate times. and i think robin and i just sat there in tears for about five, ten minutes because this is the first time we had heard him laugh. >> reporter: for "nightline," i'm deborah roberts. >> what a charming story. our thanks to deborah roberts. up next, he's the hit machine "i got a feeling." we go on the town with

will.i.am. the new taurus is going to blow people away... starting with the guys who built it. i haven't driven it yet. i'm going to try take it easy and warm up slowly. hi. do you get car sick or anything? no, is that a challenge? no, no. so with the 2013 taurus i can pretty much voice coand anything. pretty much. you're going to be able to change your radio station, make a phone call. all that you can do with just the sound of your voice. all of it? all of it. never have to take your hands off the wheel. never have to take your hands off the wheel... which is good when you're iving. ha ha ha. i wish i could keep it this way. [ male announcer ] after a dental cleaning, plaque quickly starts to grow back. but new crest pro-health clinical plaque control reduces plaque and is clinically proven to help keep it from coming back. new crest pro-health clinical plaque control toothpaste.

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not many people can say they've collaborated with michael jackson and justin bieber. and starred in a few major fi films. and wracked up six grammys. but will.i.am of the black eyed peas has done all of that and more. and tonight, he takes abc's nick watt "on the town." ♪

♪ i got that hit that beat the block ♪ >> reporter: okay, i have a man crush on a renaissance man called will.i.am. ♪ i got a feeling >> reporter: "boom boom pow" and "i got a feeling" are the most downloaded songs of all-time. will is the creative beat behind fergie and there's so much more. he produced everyone from bieber to nicki minaj. ♪ to his late els solo project, "t-h-e." he got j.lo -- ♪ and jagger involved. oh. he is also a philanthropist, an actor, here in "wolverine." a designer. and a geek. >> take the u from universal and

the neek from unique, and you -- i came up that right now. >> reporter: in london, will was giving the keynote speech at innovation night. >> what would be great would be to make that building intelligent. >> reporter: i think that, too, totally. would put sd-chips in the doorways. >> reporter: he's got credit on geek street. he's a robotic nut, ever since a meeting with dean kaman. >> he asked me to help amplify his program, keeping kids from 9 to 18 robotics. so, i was like, whoa, that's cool. i wish i was doing that when i was a little will. all things that are going to come tomorrow are going to come from you guys right here. >> reporter: will just attended their world champions in st. louis. he wants more science in schools. and -- ♪ it was a creed -- >> reporter: remember that '08

campaign song. he has the president's ear. in fact, they just had dinner. so, when you sit down and have dinner with president obama, what do you tell him about? >> america went in and had a war on drugs and lost. when are we going to fight education? >> reporter: what does he say? >> he says we're going to do that. >> reporter: he's a coach on the british version of "the voice." stealing that show with his enigmatic facial expressions. you crossed the atlantic three times this week? >> this week? four times. what part are you from? >> scotland. >> oh. oh, oh, hold on, wait. wait. the word i'm looking for is -- fit-like. >> reporter: that's scottish for "how's it going." >> do i travel or do i travel? >> reporter: that is good. he's traveled the world, but it all began here in the projects of east l.a. >> i was growing up i had the thickest mexican accent in the

world. >> reporter: did you? >> my little cousins, they talk like this. hey, will, i see you on tv. hey, london, have you meet the queen? >> reporter: not yet. but the brits did ask will to carry the olympic torch on its procession to this summer's london games. he's come a long way since his loving mom sent him clean across l.a. every day to get a great education. >> every since i was 7, i was shaking on the bus, going an hour away from home. >> reporter: you were coming home to -- >> a floor at night. we slept on the floor. >> reporter: the video for "i just can't get enough" gives a flavor of his life today. he sleeps in first class and in hotel suites. i'm not sure how he finds the time to close his eyes. i'm nick watt for "nightline" in london. >> you can watch will.i.am performing in the concert for the queen, a diamond jubilee