The Love Island contestant then explained how she descended into a pattern of self-loathing.
"I spiralled into an obsession with training to fit a certain standard. To finally be lean enough where people would stop commenting on my body and make remarks like 'wow I love how confident she is in a bikini, I could never' or 'her boobs are so saggy' or 'thunder thighs'. I honestly hated the world and I hated myself."
"So I trained. Really, really hard. I ate super clean. It was s*** and boring. I was doing it for nothing other than to be skinny enough to feel beautiful to the public. F*** THAT NOISE."
Cassidy continued: "But you want to know what the worst part is? Once photos started surfacing of me as a size 6, ribs showing, and basically nothing left of my once athletic and wonderful body. I GOT BODY SHAMED AGAIN. This time it was 'oh she’s too skinny', 'she looks better with meat on her bones', 'she looked better before'.
The 25-year-old revealed that it was at that moment that she "woke up" and had a moment of realisation.
"It was an earth shattering lesson where I told myself 'I may as well do whatever the f*** I want, and whatever will make me happy. Because at the end of the day you will NEVER please everyone'," she explained.
Cass added that she is now "a comfortable size 10," and that she's not only proud of her body but is also "so grateful" for her health.
"I don’t train as punishment, or to look a certain way. I train to feel strong. To challenge and push myself. I do it to stay sane, to give myself routine," she explained.
"I eat to nourish my incredible body that enables me to live this life the way I do. If there’s one thing I’ve learnt, it’s that words can be so harmful. You will never be able to control what others speak about you, but you certainly can control the way you speak about yourself. Remember that."
During her time on Love Island, Cassidy became the season's villain but told Who that she had no regrets.
The blonde beauty was locked in a love triangle with eventual winners Grant Crapp and Tayla Damir - who broke up just two weeks after the finale.
"I feel like I was very unique in the villa. I wore my heart on my sleeve, I was open and honest, and sometimes that caught people off guard, but I think it makes it easier for me to say I loved every moment," Cass revealed in 2018.
"I stayed true to myself, I was genuine, I was honest, and I did everything I wanted to do at that time."