"If the old me saw what the current me eats — I would not believe it," Ms Zimmerman told news.com.au
"I had worked up my willpower to go eight weeks eating 1200 calories per day and saying no to alcohol and treats."
But the moment her "challenge" was over, the Sydney local would binge and eat all the foods she had missed out on.
"This made me gain weight back fast," she said.
Ms Zimmerman said she thought "this was how you lost weight" and that she got "really good at being extreme".
"I didn't know about balance or how to not live life at such extremes."
She had struggled to find a middle ground until she discovered that eating more nutrients-based foods and lifting weights would help her shed the kilos.
"I started with my coach Ash Lane in October 2019 after we connected on Instagram," Ms Zimmerman said.
"She was telling me it didn't need to be that hard and I didn't need to eat 1200 calories to lose weight. I thought she was crazy."
"She took me from six days per week cardio training to three days per week weights training."
Ms Zimmerman did a reverse diet where she now eats 2,300 calories per day, saying the new approach has "changed my whole life".
"I have repaired my relationship with food. I now can live a balanced life while still focusing on my goals," she said.
Prior to her transformation and when she was at her heaviest, Ms Zimmerman was eating very little in terms of variety.
"I never ate salads or veggies. I ate fast food, drank coke, ham and cheese toasted sandwiches, burgers, pizza, pasta. I had a fear of trying new foods and so I would stick to the same food all the time," she explained.
As a normally bubbly person, the 34-year-old said her weight battle affected her social life and she would often use her handbag to cover her stomach.
"I wanted to hide as much as possible. I would never get to wear the clothes I wanted and shopping would give me anxiety because I would feel so helpless and stuck."
She said her 26.5kg transformation made her believe she can do anything.
"I tried and failed countless times — losing weight was a dream but I had very little faith I could actually make it happen."
"But through doing this I realised how determined, strong and tenacious I really am."
Ms Zimmerman trains three times a week now, while eating a calorie deficit to lose weight.
This means she eats fewer calories than what she burns.
"I don't cut out any food groups. I still have my favourite foods," she said. "I aimed to eat 1200 calories per day. Now I work to eat in a more modest deficit."
For breakfast she will have protein yoghurt followed by an apple as a snack and either stir fry or a taco salad for lunch. Dinners are a mixture of homemade pizza, burrito bowls or zoodle (zucchini) pasta with bolognese sauce.
For dessert, instead of having full fat ice cream, she opts for a Halo Tops' 280 calorie tubs.
Ms Zimmerman has gone on to develop a passion for health and fitness, creating an Instagram page dedicated to her journey that she said is also to "hold her accountable".
"Through sharing on my Instagram and being so vulnerable and open it has taught me to not be ashamed or embarrassed of where I have come from but celebrate my story so far."