Trainor, 21, said she used to feel bad looking at her own pictures during the early stages of her career, reported Us magazine.
"When I saw photos of myself, I would think, I look awful. There's a double chin! I never thought I'd be a pop star. I don't look like Rihanna," she said.
Trainor's under confidence about her appearance and pessimism about her future only changed after the release of her smash single, 'All About That Bass' last year.
"It's a mental thing. Just recently I was thinking, 'I'm confident now, and I look good,' and that's because I've started saying those words out loud more. So now when I see pictures, I'm like, 'Oh my God, why would I hate myself at all? I look incredible in that picture!'" the singer said.
Trainor feels every woman should be confident about herself and believe in her dreams.