No advertising, no investment and no debt: How Spanx's Sara Blakely became the youngest self-made woman to join Forbes' World Billionaires list

So famous is Spanx, that whenever a we see a glimpse of a celebrity's slimming undergarments, the brand name almost inevitably appears in the headline.

And it seems that the A-list aren't the only ones, as the company's founder, Sara Blakley, appears this week on the cover of Forbes' Billionaires issue.

The 41-year-old, who originally hails from Florida but is now based in New York, is the youngest self-made woman to make the list.

Hose that girl Sara Blakely is Forbes' youngest self-made billionaire thanks to the invention of Spanx

Hose that girl Sara Blakely is Forbes' youngest self-made billionaire thanks to the invention of Spanx

The magazine reveals how the founder of a company that is estimated to be worth about $1billion is scared of heights, flying and speaking in public.

And yet despite these crippling fears, Ms Blakely, has made her fortune largely as a one-woman show, travelling cross-country for in-store demonstrations and taking customer service calls from her bathroom at home.

A one-time Disneyworld employee, Ms Blakely found her real calling when hawking fax machines door to door for Danks, an office stationary supply company in Florida.

Uncomfortable in the sticky humidity she was desperate to find a pair of pantyhose that didn't have seamed toes and that didn't roll up the leg when she cut them.

Gwyneth Paltrow wore Spanx to the Vanity Fair Oscar party shortly after giving birth to Apple in 2005

Octavia Spencer wears Spanx under her gown at the Golden Globes this year

Emily Blunt at the Oscars in 2007 wore a full body Spanx

Figure-hugging fans: Gwyneth Paltrow (left), Octavia Spencer (middle) and Emily Blunt (right) have all confessed to wearing Spanx on the red carpet

She explained to Forbes: 'I’d never worked in fashion or retail. I just needed an undergarment that didn’t exist.'

After setting aside her life-savings of $5000, the aspiring hosiery maven moved to Atlanta and threw herself into research, knocking on factory doors to get her new product manufactured.

To save the $3,000 legal fees needed to patent the name she used a Barnes & Noble textbook and learned how to do it herself.

Of the brand, Ms Blakely said: 'The word “Spanx” was funny. It made people laugh. No one ever forgot

Without a penny to spend on packaging or advertising, the wily entrepreneur spent evenings on a friend’s computer designing her logo and reading up on marketing tips.

Slimline: Plans for expansion of the brand include a diffusion line

Slimline: Plans for expansion of the brand include a diffusion line

In the Forbes story she recalled being caught on a CCTV camera in a department store repositioning her products so they were displayed more prominently.

The character and charm that she relied on to launch her business was noted by current CEO of Neiman Marcus, Karen Katz, who saw
her first ever pitch.

'Sara’s effort was to solve an age-old problem for women in a
modern way,' she said, adding: 'We were smitten from the beginning.'

When Oprah announced on her show that Spanx was her favourite product of the year in 2000, despite not even have a website, the business exploded.

In its first year, the company, that is still owned entirely by Ms Blakely, fetched $4million in sales with an impressive $10million the next.

And all the while, she has never spent a cent on advertising or relied on support from investors.

These days nine catalogues are mailed to six million shoppers every year and the founder is plotting for expansion with her long-standing CEO Laurie Ann Goldman.

Plans including stand alone stores, a cheaper diffusion line and a swimwear line.

Of the newly earned wealth that affords her six homes with husband Jesse Itzler and their two-year-old son, Lazer, she said: 'I feel like money makes you more of who
you already are.

'If you’re an asshole, you become a bigger
asshole. If you’re nice, you become nicer. Money is fun to make, fun to
spend and fun to give away.'

And then thinking about that her humble beginnings added: 'Five grand. Good investment.'