"They said I had a huge jaw. They said I had a 'potato head,' " she told HuffPost. "When you're 14 or 15, I didn't really understand having value in myself yet.
"My mind went to, 'Okay, so if I get skinny or if I dress the right way or present myself very hyper-sexually and dress this way, then I'll be valued.'"
Willis said she began to think her value was decided by if she was "desired by a man" rather than "what I thought about myself".
But fortunately her mother Moore turned things around and reminded Willis not to pay attention to the unkind things being said about her.
"I definitely talked to my mum, and her thing was always, you can't read the comments," she said.
"You could post the most beautiful picture about how you've gone and you're helping kids or you're giving your time and someone will still find a way to rag on you."
Willis also hit out in her interview at a photographer which she called out for photoshopping her jaw in 2016, telling HuffPost it was "really offensive".
"Whether or not they realise it, it is a form of bullying, which I won't stand for," she added.