Fat: If You Can't Burn It, Freeze It?

Feb. 9, 2011 — -- Barbara Knoth, a schoolteacher, is like a lot of women over 40.

"I've always been thin. I've never had a problem with my weight. And then, all of a sudden, this belly fat started to appear. I walk, I jog, I go to a gym but no matter what I did, this would not go away," Knoth said.

Knoth is also part of a growing movement of women eager to avoid cosmetic surgery.

"I don't want to go under the knife and [get] anesthesia," she said.

Instead, Knoth is getting a new treatment that's simple and pain free -- freezing her fat away.

"It's like a vacuum. But once it's been on for a couple of minutes, you really don't feel anything," said Knoth.

The one-hour treatment is called Zeltiq and was just approved by the FDA. A vacuum like device pulls in those annoying bits around the middle and literally freezes them. The fat cells die a slow death over 6 to 8 weeks and the results are dramatic.

"It's incredibly popular," said Dr. Debra Jaliman. "I mean, first of all, when people first hear about it, they think it's too good to be true. They can't even believe it. And then when I explain it, they say, "Does this really work? But the patients we've done, they've just been ecstatic."

"I've been in dermatology for 25 years," said Jaliman, "and I never expected to see this."

In its ability to target a specific area, Zeltiq is similar to liposuction. But it's not surgery, and the lack of pain and recovery time has made this one of the hottest treatments, so to speak, that Jaliman offers. But results are not immediate – they can take five to eight weeks.

"It's a gradual change because it went over, I guess, about six weeks. And I kept on looking and looking and said 'I don't see anything, I don't see anything.' But you're not going to see anything because you're seeing yourself every day. It wasn't till I saw the pictures, that I realized how much belly fat was gone," said Knoth.

The new treatment is the brainchild of Dr. Rox Anderson of Harvard University and Mass General. A laser specialist who invented laser hair removal and spends most of his time removing debilitating scars and marks from children, he started wondering about the effects of cold a few years ago.

He thought about two things: Incidents where infants sucked on popsicles for too long and lost the fat in their cheeks, and the fact that butter fat hardens, or freezes for that matter, more quickly than a lot of other things, like skin. Which means you can kill the fat cells below without doing any damage to your skin.

At this point, the technology is best suited for people with a bit of extra fat.

"So people who are in good shape, who have a healthy diet, they're exercising and they have body fat distribution still that they're not happy with, they are the ideal candidates for this," said Anderson.

"When we speak to our patients we are very clear to tell them that if they're eating 4,000 calories or 10,000 calories, they can't continue that because then they're just going to get fat deposits somewhere else. So this is not a license to eat as much as you want – eat all the junk food you want," said Jaliman.

Women aren't the only ones rushing to try the new procedure.

"This is one of the cosmetic procedures in our practice where it's really split half and half. It's not painful, it's not invasive, yet it works," said Dr. Jaliman.

That concept drew Lisa Marcs to the office, but with a different goal. She wanted to tighten her face with no knife and no fear of that stretched look.

"I like the fact that there was no cutting involved; no down time," said Marcs.

In this procedure, called thermage, radio waves trick skin into producing more collagen. And a recent upgrade to the technology now can produce results comparable to a very natural face-lift. In a few hours. With no surgery."

"We've had patients check into our office to do their whole body with thermage. Hands, neck, legs, all over," said Jaliman.

The only pain involved is that on your wallet. Fat freezes start at $750 and thermage starts at $1,000. But to some, it's money well spent.

"I saved to have this done. I'll be honest with you. I put the money aside. Uh, this is like, you know, a vacation for me. But it was, it was worth it," said Knoth.

Viewers submitted lots of questions about these procedures to our web site today – you can read a doctor's answers to the most common ones at ABCNews.com/Nightline.