Aussie mum's 41.5kg weight-loss on 'Kmart diet'

Sarah shared her incredible transformation on the Kmart Mums Australia Facebook page. Photo / Supplied

A New South Wales mum, fed up with not fitting into clothes from her favourite store, has transformed her life — losing almost 42kg on the "Kmart diet".

Sarah Hill, 28, from the Hunter Region (north of Sydney), shared some before and after photos of herself in two different Kmart outfits, saying she was proud of herself for "working my butt off" to lose the weight.

The post quickly went viral, attracting more than 7500 likes and hundreds of comments of support for the young mum's "incredible transformation".

Posting to the Kmart Mums Australia Facebook group's 333,000 members, Sarah revealed she now fits into a Kmart size 12, but the secret behind these photos is what has everyone talking.

Sarah weighed 130kg at her heaviest in 2016. Photo / Supplied

Speaking to news.com.au, the mum-of-one said she weighed 130kg at her heaviest, which restricted her to buying clothes only in sizes 24-26.

"At that size, my options were so limited, it was really hard to pick up an affordable outfit at Kmart or Target," Sarah said.

"I would walk into Kmart, see all the gorgeous clothes I desperately wanted to try on and just keep walking straight to the plus-sized section."

Sarah said her size made it difficult to buy nice outfits. Photo / Supplied

Sarah said she had put on weight during a relationship that didn't work out, but it was only when it ended she realised her weight had ballooned.

"When you're in a relationship, prioritising your health goes straight out the window," she said.

"I just wasn't myself, mentally and physically, and I wasn't giving my all to daughter Abby."

Sarah ended the relationship in 2016 and was "horrified" when she learned she weighed 130kg.

"It was the biggest I had ever been, and it was terrifying," she said.

"It was really the tipping point for me."

Sarah (pictured far right in black shirt) decided: "That's it, I'm done!" and joined her local boot camp. Photo / Supplied

After, Sarah enrolled in a free bootcamp in her neighbourhood and went to classes four times a week, with Abby strapped into the pram beside her.

"When you're the biggest and slowest person by far, all you're thinking about is how everyone was probably judging and laughing at you," she said.

"It was embarrassing for me to put myself out there, but I just told myself that everyone has to start somewhere."

Sarah (white singlet) stayed dedicated to her fitness and made friends along the way. Photo / Supplied

The busy mum-of-one started out going to a free boot camp close to her home. Photo / Supplied

She also reduced the size of her meal portions and began the 5:2 diet, which incorporates two days of intermittent fasting.

According to Sarah, the main motivation for her weight loss was to be able to fit back into the Kmart clothes she'd admired for so long — dubbing her new healthy lifestyle the "Kmart diet".

"I paid attention to what I was putting in my mouth and was being as active as I could," she said.

Sarah also took on part-time work and raised enough money to join a gym.

"If I can't make it to the gym I try and make time at home to do something, and I definitely still love the odd treat now and again".

Sarah went from weight 130kg at her heaviest to a healthier 88kg. Photo / Supplied

After dropping an enormous 42kg, Sarah recently walked into Kmart to try on her first outfit since her dramatic weight loss.

"I would usually wear jeans all summer, I never wore shorts or revealing outfits," she said.

"So when I tried on that midriff top and skirt, and realised it was a size 12, I couldn't believe it.

"I wanted to be able to walk into a store that wasn't a plus-sized shop, see something cute, get it in my size and feel confident in it."

"That's just not something you can do when you weigh 130kg. It's an entire process to go shopping."

The moment she slipped into the size 12 outfit, Sarah said she couldn't wipe the grin off her face.

"It was the first summer outfit I had worn where I felt confident showing a little bit of skin. I felt like a young woman again, and I can't describe how happy that made me," she said.

Sarah said she loves the feeling of picking up a cute outfit without any hassles. Photo / Supplied

According to Sarah, her relationship with daughter Abby has also improved since the weight loss, and she now has a new partner, Tyler.

"It's so nice to have the confidence to play with Abby and hopefully teach her to have the same self-worth," she said.

Sarah said she loves having enough energy to play with her daughter. Photo / Supplied

Sarah's story prompted massive support from the Facebook group members, with many congratulating her on her transformation and asking what her secret was.

"Wow you should be very proud of yourself," one member wrote.

Others said the mum's incredible photos had left them "speechless".

"Wow you're incredible! Amazing! You look fantastic!" another member wrote.