BOSTON -- There is some new thinking in the age-old quest for youth.

NewsCenter 5's Heather Unruh reported that many dermatologists and plastic surgeons now believe it's not wrinkles making you look older -- it's the loss of fat in your face. Some local doctors are using interesting techniques to fill out faces and bring back that youthful look.

Karolyn has tried a whole host of products and injections to smooth out the lines on her face, but she said that she got some of her youth back after one treatment with a new product called Sculptra.

Sculptra doesn't really turn back the clock, but it does smooth wrinkles by filling out your face.

"As we age what happens is we lose our fat and our face starts to have volume depletion and that's what gives you that much more aged look," Dermatology Partners Dr. Ruth Tedaldi said.

Sculptra claims to bring back the volume to your face through a series of monthly injections of a biodegradable polymer. It's not easy or cheap -- each treatment consists of about 50 separate injections and costs between $2,000 and $4,000 depending on how much volume you need.

"It's not something that will be gone in six months. It's something that will last up to two years, so I feel the investment is worth the money," Karolyn said.

"Sculptra, by study, has been shown to last longer. The jury's out for me," Tedaldi said.

What may last the longest is replacing your fat with fat. Cosmetic surgeon Niels Krejci-Papa just returned from the West Coast where volume replacement is rapidly replacing the nip and tuck.

"It's really turning the time back and making the patients look like they used to look like not like someone who has aged and had facelift," Krejci-Papa said.

Fat is harvested from areas of the body that don't respond to dieting -- like the abdomen, hips and thighs -- and then injected into the face. The results are visible and practically permanent.

"That characteristic stays with the fat so if you put it here and they go through dieting it will stay it will not go away," Krejci-Papa said.

Krejee-Papa said that it helps to bring a picture of yourself when you were younger so he can actually try to recreate the same look you had then.

Fat replacement is also costly. It's about $2,500 for the initial treatment with follow up sessions costing about $1,000 each.