Demi hit her lowest weight of 7st in 2015. She said: “It got to the point where I would look in the mirror and I was unrecognisable.
“I was stepping on the scales and realising just how low the numbers were.”
She put on half a stone and convinced herself she had recovered, but was still desperately thin.
Anorexia stopped sociable Demi going out with friends, and soon she was only interacting with people through YouTube make-up tutorials.
She said: “I felt like they were like friends, because I was so isolated.
“It was the only time I wasn’t consumed by my eating disorder. I wanted to make videos and work as a make-up artist.
“But, at 18, something just snapped and I realised that if I wanted the life I was envisioning, I couldn’t do it if I was sick, or if I had to spend all day in bed – too thin or depressed to do anything.
“I felt like I was wasting my life.”