The change in posture? The way they transform an outfit? Or even a power rush that sweeps through your body when you put them on? Experts, fans, designers, and celebrities try to explain their love for heels in God Save My Shoes.

Director Julie Benasra set out on a quest to talk to everyone from burlesque dancer Dita Von Teese to the Black Eyed Peas' Fergie, from Christian Louboutin to Manolo Blahnik, and to all imaginable kinds of shoe fetishists around the globe to look at the phenomenon from a "psychological, sociological, historical, cultural, and erotic perspective."

Judging from the just-released trailer, many of them have trouble putting their passion into words, with designer Pierre Hardy saying, for instance: "I don't know where this thirst for shoes comes from, but it doesn't go through reason...for some girls, the shoe is a compulsive thing," and marketing consulting company Just Ask A Woman's Mary Lou Quinlan agrees: "This is about want, it isn't about need, you don't need 60 pairs of shoes." Hardy's colleague Louboutin even goes as far as claiming that "women have a carnal relationship with their shoes."

One of the most eloquent explanations, at least in the trailer, comes from an American Vogue editor: "One element that goes on your feet can actually change the mood of your entire look, your entire behavior. I mean, that's power."

The documentary is set to launch during Paris fashion week this fall. In the meantime, short teasers can be found on the film's Facebook profile. A 'production diary' about Christian Louboutin is already live.

Women's (and some men's) obsession with shoes has previously been the focus of the musical Shoes at London's Sadler's Wells theater, while fashion documentaries as a whole - new launches include This is my dream on Yohji Yamamoto, Bill Cunningham: New York on the legendary street style photographer, and L'Amour Fou on the relationship between Yves Saint Laurent and Pierre Bergé - continue to fascinate the fashion crowd.

Watch the trailer at