Tonight on abc's "the lookout," calorie burn, "the lookout" turns up the heat. I'm now like totally drenched. The latest weight loss trend, high technicalry burning machine. You won't believe what we... See More
Tonight on abc's "the lookout," calorie burn, "the lookout" turns up the heat. I'm now like totally drenched. The latest weight loss trend, high technicalry burning machine. You won't believe what we put our people through. Is it physically possible to burn 2400 calories in an hour. Let the calorie count begin. And the fine print. Let's face it. It's tiny, there is lots of it and you're probably not reading it, or hearing it. Careful, we're taking it to the street to help you focus on what you're really signing up for. Is that like an equal sign? I'm not sure what that is. And show you what to look out for. Tonight we're telling you what to look out for the fine print. We're taking "the lookt" ice cream truck to the street. What's your favorite ice cream? Vanilla. Does vanilla mean impressive? Does passionate mean you like chocolate? What about rocky road? It's ice cream confidential and we've got the scoop. We're going to help you do whatever it takes to help you get more out of your money. Seems like everybody is trying to sell you something these days. Which is why tonight we're on the look out for you. First up, calorie burn. Hot and sweaty. I know. I look ridiculous. The wig, the sweat, the funny sleeping bag. I am now glistening with sweat. But I'm undercover checking out a trendy device from the billion dollar complex, loose weight without dieting by burning loads of calories in this cocoon. I'm being showered with infrared. Frankly, I kind of need a shower. That's the fit body wrap, makes claims of burning up to 1400 calories an hour while doing nothing. This isn't the only gadget making huge calorie burning claims. Here's my producer erin. They say you'll burn up to an astounding 2400 calories in minutes. That sounds like my kind of workout. We need to investigate, incognito. Now I'm blondiblondish. I'm off to brooklyn in disguise for my sweaty session at the day spa. These are undercover glasses. Camera is right over here. Is that okay? For the purposes of this shoot my producer erin is pretending to be my friend, treating me to a spa treatment. This one is ju ju's. This is a camera. That's your audio. Like a clutch. And brake. Want to stop for a frank burger? I'm sure it's no good to have a frank burger before your workout. Listening in a weight loss expert with another producer. Hi. How does it work? Basically it emits -- it heats up to 130 degrees. The very fit, very friendly man is very enthusiastic about the benefits of fit body wrap. It's awesome, it's not only for weight loss. It's really good for joints, helps with circulation. But the headline for dieters. It's equivalent to running six to nine miles on a treadmill calorie-wise. Does it really burn that many calories though? Yeah, it's awesome. How many calories was it? 1200 to 1600. Can you possibly burn that many calories without doing anything? If it's just about heating your body up, then people in hot climates should be thinner. I feel like I'm in costume but it's warm and comfy cozy. It's been 25 minutes. I am now beginning to panic. You can make it. Don't panic. I'm serious. I'm so hot in this thing. Somebody is no longer a happy camper. We're 45 minutes in. I'm now, like, totally drenched in sweat. Reporter: Research has found benefits from infrared, easing stiff muscles and joints, soothing rheumatoid arthritis and cardiovascular benefits but when it comes to calorie burning and weight loss -- get me out of this thing! Reporter: The evidence as we'll see is thinner. I'm literally so happy to be out of there. Reporter: Back at the van, the professor has disappointing news. While he estimates that I lost a pound or two, he says it's probably all water weight that will soon return, not what a dieter wants to hear. Right now I feel a little light-headed actually. What you have done is sweat. You might lose inches and weight shifts around, but that's different than burning body fat. Reporter: So what about those giant calorie burning claims? It would be a revolution and talked about among weight loss experts nonstop, nonstop. Reporter: Okay. But I was just lying there. What about that other infrared contraption that involves actual exercise? It's the fizz yoe red. Half bike, half sweat box. It definitely ups the ante but can it measure up? That's the co-owner of the health spa in new jersey, chatting up erin, our undercover producer. You will burn on a typical session of a half-hour around 1,000 calories. Reporter: In 30 minutes? Wow. The maker goes even further, up to 2400 calories in 40 minutes. Oh, wow it's really warm. Reporter: Soon erin is sweating up a storm. Between pedaling the bike and laying in the bag, these huge calorie claims cried out for a reality check. So I went for a slow jog with this guy. He lectures on exercise physiologist at usc, calorie burning his specialty. How many calories am my burning? Right now if you would come this up for about an hour you would probably go to 250 calories. But I'd have to be jogging for an hour? Yeah, exactly. I'm not doing that. Reporter: Why should I when right here it says I can pedal their bike and burn up to 2,000 calories. Is it physically possible for me to burn 2400 calories in an hour? Physically impossible. Reporter: This is dr. Ray jalian. He doesn't see enough evidence to support the huge calorie claims. Billions of dollars are spent on obesity research every year. Would I be surprised if a body wrap that you wear for 40 minutes is a cure, yeah. You might lose inches and weight shifts around but that's different than burn body fat. Before the fizz yoe red bike. You cannot burn 2400 calories in an hour. Reporter: The experts aren't buying it which means we have to make some return visits. This time, no wigs, no hidden cameras.
This transcript has been automatically generated and may not be 100% accurate.