The Little Mix singer has revealed the impact online bullies had on how she saw herself, and she admitted seeing positive comments after losing weight meant she convinced herself she was doing the right thing.
She told The Guardian newspaper: "I'd starve myself ... I'd drink Diet Coke for a solid four days and then, when I felt a bit dizzy, I'd eat a pack of ham because I knew it had no calories. Then I'd binge eat, then hate myself...
"I could see that I was losing weight and sometimes I'd see a few good comments and that spiralled me to be like: 'This is how I need to stay.' No one cares whether your performance was good, or if you sounded great."
The 28-year-old star - who also opens up about trolls and mental health in her new BBC One documentary 'Odd One Out' - felt pressure to represent and defend every woman while preaching about confidence.
She added: "I felt I had to be this person who was like... 'I don't care what people are saying about me, I'm this strong woman.'
"That was the role I had to take on in the group, when really I was an absolute mess."
In the documentary - which will air on September 12 - Jesy explained while she loves being part of the 'Black Magic' band, the cruel comments really took their toll.
She said: "Being in Little Mix is just the best thing that's ever, ever happened to me. But I hit such a low point in my life that I stopped turning up for work.
"From the minute the comments started it got worse and worse. My brain started to believe everything people were saying about me. I felt embarrassed. I felt ashamed."