At 45, fitness expert and first-time mother Michelle Bridges wants to tackle the fast food industry in the same way the tobacco industry was tackled 50 years ago.

Bridges said having her own child had encouraged her to put out some hard-hitting messages about the junk food and sugar industries.

“The truth of the matter is they sell crap food and make people sick,” she told the ABC’s Australian Story program.

Bridges found fame as a tough trainer on The Biggest Loser. Photo: Supplied

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The star of TV’s The Biggest Loser weight loss reality program said it made her angry to see the effect of fast food on children.

“We’re now seeing children who potentially have a lifespan shorter than their parents — never before have we seen that globally,” she said.

“I’d like to get out there and start fighting the fight for others who can’t fight the fight.”

Bridges has been described as Australia’s most influential health and fitness expert, with a growing business empire that last year saw her named on the BRW list of Australia’s richest self-made women.

But she had humble beginnings as the daughter of a broken home in working class Newcastle, in New South Wales in 1970.

Money was so tight that her mother, Maureen Partridge, could afford only one school uniform.

“It was a case of wash it each night, hang it on a little inside line, get up in the morning and iron it, so she had a clean uniform each day,” Ms Partridge said.

Her family moved house so many times that Bridges was bullied as the perennial ‘new kid’ at school.

Then she discovered that sport offered her a way of dealing with the bullying and made her feel strong and free.

“I fell in love with the competition of netball, basketball, hockey, soccer, water polo and equally I fell in love with the commitment and the discipline of training,” Bridges said.

– ABC