alicia keys tight pants shapewear

Alicia Keys keeps it tight on stage. Photo: Jason Kempin, Getty Images

Looks like corsets aren't the only body-cinchers getting a star-studded boost.

Slimming shapewear garments have seen a 10.6 percent increase in annual retail sales from March 2009 to February 2010, plus a 3.8 increase in unit sales according to figures from The NPD Group.

And it looks like Spanx might want to send a Hallmark card to Hollywood as a show of gratitude.

Celebrity Spanx devotees like Gwyneth Paltrow, Oprah Winfrey and Jessica Alba have reportedly sparked a rise in the popularity of shapewear, while corset and garter-loving gals like Lady Gaga and Beyonce have also gotten shoppers' knickers in a twist.

Retro-themed television shows like "Mad Men" and "The Tudors" have also reportedly put the undergarments front and center.

"We started seeing this happening about two years ago with red carpet-ready celebrities saying, 'I've got my Spanx on,'" Maureen Stabneau, senior vice president of merchandising for BareNecessities.com, told WWD.

"It also became a secret weapon for celebrity stylists, and shapewear came out of the closet," she said. "Our shapewear business is doing very well, and our plus-size shapewear business is ahead by 25 to 30 percent over the past year. It's not necessarily about being smaller; it's about making you look smooth."

According to the NPD, shapewear in sizes XL-XXXL and up saw a sales growth of 14.8 percent.

"Lady Gaga, Rihanna and Beyoncé are huge in this equation," Robert Thompson, professor of television and pop culture at Syracuse University's S.I. Newhouse School of Public Communications, told WWD.

"There has to be something of a fashion authority, something that shows people looking good in what they're wearing, whether it's prime time TV, a fashion show in Paris or an ad in Vogue.

"If it goes to the extreme item such as Lady Gaga or Rihanna wearing foundations, you will see a huge interest all of a sudden in something like a corset. That's when it gets to be a smoking gun.

"As brilliant as 'Mad Men' is about Americans in the early Sixties -- the show makes old Fifties girdles look so fabulous under clothing -- it's more brilliant as an ad for undergarments."

As we've reported previously, labels like Victoria's Secret and Cynthia Rowley have also recently added shapewear lines.

And let's not forget Spanx for Men! Although we really hope that's the only fashion trick our fellas pick up from Lady Gaga.

Meanwhile, check out hot shapewear trends for Spring 2010.