The star, 32, said that her knock in confidence had been fuelled by the lack of "curvy younger women" on TV.
Last year, the former pro dancer departed the hit BBC dance show after seven years, having joined the cast in 2015.
Speaking to The Times about the pressure she feels to be slim, she said that it "doesn’t come from people saying anything, it’s from what you see” because “you don’t see a lot of curvy younger women” on screen.
Mabuse blames subliminal messaging from the whole TV industry that rewards female stars for being thin.
She explained: "If that’s the trend, should I be following the trend?
"If that’s what the brands are pushing, if that’s the people who are getting the big shows, if that’s what they look like, then you think that is the standard.
"It plays in your subconscious – that does the math."
This is in contrast to how Mabuse – who has since become a judge on Dancing On Ice – felt on Strictly, where she was comfortable as one "of the curvy girls”.
She said: "I think I was relatable for a lot of women because all the girls are really petite...only when I didn’t dance any more and you could see me sit and you’d be like, ‘Oh, she’s got boobs. Oh, she’s curvy.’"
The star noted that her body had changed since reaching her 30s, and said that she is "never going to be a size zero".
She added that she is "healthy" and "happy" finding balance in her lifestyle, in which she can eat pasta for breakfast and then go to the gym.
Watch: TikTok dance by Oti Mabuse raises awareness about performing CPR