Gabrielle says she “battles every day” not to make “fat girl comments about myself”.
The Dreams singer, 50, told The Big Issue magazine she began thinking negatively about herself when she hit the limelight.
“When I entered the music industry I became really self-deprecating,” she said.
“I once opened up a newspaper and it had an article about the five fattest girls in pop – I was one of them and so was Geri Halliwell, who’s teeny weeny weeny.
“No wonder people had eating disorders.”
In a letter to her younger self, she told the magazine: “I have got to a place where it’s OK to be me but I battle every day to not make fat girl comments about myself to people.”
She continued: “It’s OK to trust your gut. It’s OK to believe in yourself. It’s OK to not always listen to those who claim they’re telling you things for your own benefit.
“Sometimes we listen to people who actually have their own agenda, and even if they’re close to us or loved ones, I would tell my younger self it’s OK not to always take that advice.”
The Big Issue with the full interview is out now.