Could it be those workout tapes? Or beauty secrets the rest of the world is naïve of? Jane Fonda defied age on the red carpet on the first day of the 2012 Cannes Film Festival, posing the question to many: How on Earth can this woman be 72-years-old?

Wearing an Atelier Versace bronze gown, Fonda showed how gracefully she is aging, putting other stars half her age to shame on the 65th annual Cannes red carpet Wednesday.

Fonda successfully did it again on Thursday for the screening of Rust and Bone, donning a form-fitting, two-tone gown in black-and-white by Stella McCartney. According to the Hollywood Reporter, Kate Winslet wore a similar, shorter design to the 2011 Venice Film Festival, as well as Liv Tyler, Nicole Scherzinger and La La Anthony on different occasions.

The black-and-white McCartney dress has a slimming effect thanks to the dark colors on the outside of the dress, creating an hourglass form and slim waist. According to the Hollywood Reporter, the trend first appeared on the Spring 2009 runways thanks to designers Alexander McQueen and Herve Leger.

But is the dress, a great exercise regimen or just Fonda?

Amongst her many talents and career highlights, it can be argued that Fonda is most known for her workout videos. After training under Leni Cazden, the fitness guru released the Jane Fonda Workout video and book series in 1982. Selling over one million copies, the video quickly became one of the most successful home videos, prompting Fonda to release more than two dozen more.

Most recently, Jane Fonda donned her leotard again in 2010 to release two more videos, Prime Time Walkout and Jane Fonda: Prime Time Fit & Strong, aimed at older folk.

I'm very excited to be back in the fitness business, she told People. I know from experience and from my research how critical it is for seniors to be physically active. Even if they've never exercised in their lives, now's the time and my programs are a good, safe way to do it.

View the photos of Jane Fonda on the red carpet at the 2012 Cannes Film Festival.