The determined 36-year-old decided to turn her life around and has since shed 121kg.
Married Sarah, who now weighs 99kg and wears a size 16, said: ‘I was always a bit overweight as a kid, but it wasn't until I was about 13 that my food addiction really took hold of me.
‘I would eat amounts that are just not humanly possible and was always looking for ways to get more food. I would honestly lie in bed and think 'this is it, I'm not going to wake up tomorrow'. But then I'd get up the next morning and do it all again. It was a vicious cycle.
‘It was an absolute addiction. I couldn't stand feeling like there was any space left in my stomach. I was out of control. I didn't realise it at the time, but I was extremely depressed, lonely and just miserable with my life.’
After her food addiction started in her early teens, Sarah continued to pile on the kilos until she tipped the scales at 140kg at just 19 years old.
But she said that was only the beginning of her destructive habits and she continued to put on weight and 'abusing' her body for another 10 years before she sought help.
Her poor diet and total lack of exercise left every day feeling like 'a struggle to survive' and making even the simplest tasks - like fitting into public toilets - impossible.
But everything turned around aged 31 when Sarah's company offered her a once in a lifetime job opportunity to leave Adelaide behind and move to Melbourne.
And while packing her belongings, she stumbled across an old letter a friend had written in 2004 pleading with her to lose weight- and the 'wakeup call' saw her transform her life.
Sarah believes at her biggest she weighed 220kg, but her first official weigh in didn't come until after four months of dieting and exercising, at which point she weighed 211kg.
After losing 50kg on her own, she decided to take the plunge and went under the knife for gastric sleeve surgery.
Sarah is also now training for a fitness certificate so she can help others and has more than 1,000 Instagram fans following her ongoing weight loss journey.
Sarah said: ‘My life was so lonely and miserable, I wouldn't even really call it living.
‘People don't realise how hard it really is for an obese person just to exist in the world. I'd always turn down different opportunities because of my size.
‘But when I got this new job I knew it was my chance to start a new life and be the person I've always wanted to be.
‘That letter was a sign from the universe that this needed to happen now to save my life.
‘I started by making better food choices and trying to move more.
‘Then I joined a gym. On my first day, I could only walk for six minutes at an extremely slow pace before I was exhausted. But I went, and from then I just built up my strength.
‘I'm finally at peace with myself. I have a whole new life and I've never been happier.'
SARAH'S DAILY DIET: BEFORE
Breakfast - Coffee and red bull (220 calories) Morning Snack - Packet of chips and a chocolate bar (600 calories) Lunch - Large meal, usually a big roast dinner or chicken parmigiana with chips (1,400 calories) Afternoon snack - two large burger meals or a family box from McDonald's (3,000 calories) Dinner - two large pizzas and a garlic bread delivered (3,600 calories) Dessert - two family sized blocks of chocolate or a whole tub of ice-creams (2000 calories)
Total: 10,820 calories
SARAH'S DAILY DIET: NOW
Breakfast - two eggs (140 calories)
Morning Snack - cucumber sticks and cherry tomatoes with homemade dip (150 calories) Lunch - Grilled chicken and vegetables or tuna salad (350 calories) Afternoon Snack: Protein bar or protein shake (150 calories)
Dinner: low carb and protein-based meal such as meat with vegetables or salad (400 calories)
Dessert: a piece of fruit (80 calories)
Total: 1,270 calories