Outspoken fitness trainer Michelle Bridges has declared war on “crap food”, while prompting accusations of fat shaming.

In Monday night’s Australian Story devoted to her life, the high-profile personal trainer said she feared junk food will shrink the lifespans of Australian children – a concern that grew after the birth of her first child.

“The truth of the matter is they sell crap food and make people sick,” Ms Bridges told the ABC.

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

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Ms Bridges said she wanted to “tackle” fast food in the same way the tobacco industry was targeted five decades ago.

It continued a warpath The Biggest Loser trainer began in 2007, when she joined the weight-loss reality TV show, an endeavour she ultimately believed could improve happiness.

Some of her comments during the Australian Story episode prompted fierce backlash.

“I think it might be seen that I have this agenda on people who are overweight or people who are deemed fat. Honestly if you are happy where you are, genuinely, more power to you,” she said.

“But I can tell you now, I am yet to have met someone who is morbidly obese and happy.”

Writer and comedian Catherine Deveny responded angrily to this comment on Twitter.

Dear Michelle Bridges, fat, happy, having a wedding, riding a bike. I wished you had spoken to me before this photo. pic.twitter.com/5Xg7Waegol

— Catherine Deveny (@CatherineDeveny) April 18, 2016

“Michelle Bridges here’s a happy obese person! Loving your body exactly as it is is an act of civil disobedience,” Deveny wrote in an earlier tweet.

Another, @BoopleSnoople, tweeted: “Michelle Bridges saying she doesn’t know any happy overweight people. It really feels like she enjoys making people feel inadequate.”

‘Lifespan not the main problem for Australian youth’

Recent figures from the University of Sydney showed more than half of the Australian population consumed excessive amounts of added sugars, particularly from ‘occasional’ treats like sugary desserts and soft drinks.

Although unhealthy diets, combined with a lack of movement, was impacting public health, one public health expert has said they were not convinced junk food was shortening the lifespan of Australia’s children.

But there was a more pressing issue to combat.

“What does worry me more than our children dying earlier is the number of our children who will end up being diabetic, who are going to spend a higher proportion of their adult life with a chronic condition, which will reduce the quality of their life and their ability to contribute fully throughout life,” University of Sydney Boden Institute professor of public health nutrition, Timothy Gill, told The New Daily.

There has been a decline in the consumption of sugar-sweetened beverages. Photo: Getty

“In the past … most people would develop [type 2] diabetes in their 60s or 50s at the earliest, now we are seeing it develop much earlier. We are seeing people in their 40s and even teenagers developing this form of diabetes.”

In a recent move towards transparency, Mars Food, which owns the Dolmio and Uncle Ben’s brands, announced they would label their meals products that were high in salt, fat or sugars as ‘occasional’.

Other recipes would be changed to increase their nutritional value – a move that likely wouldn’t make the meals hugely nutritious, Prof Gill said.

One of the success stories in the fight to improve public health was a decline in consumption of sweetened beverages.

Sweet syrup cordial saw a decline in sales to $164 million, Nielsen Homescan data indicated – a drop of nearly 6 per cent by value, and more than 11 per cent in volume in the year to October 2015, News Corp reported.

“It does seem we are reducing our intake of sugar-sweetened beverages which is a positive sign, but having said that most of the improvement comes in very young age groups,” Prof Gill told The New Daily.

“Teenagers and young adults continue to consume enormous amounts of sugar-sweetened beverages.”

-with Anthony Colangelo