The 36-year-old former Pussycat Doll spoke to TheEvening Standard during her album launch at Café Royal in London's Regent Street on Tuesday. She described the writing process as a form of "therapy" which helped her overcome self-esteem issues.
"I wasn't enough, that I wasn't pretty, that I was fat, and that I wasn't worthy of more," she explained to the newspaper.
"It's a very personal album to me. It's a transitional album, and it's very honest and authentic.
"Everyone always has these pre-conceived notions - that you're glamorous, you don't have any problems, you don't have any issues, and we all battle with our own issues."
Nicole also revealed how writing the album helped her move on from the past.
"I'm in a different place in my life now," she added. "I feel a bit more confident and comfortable in my own skin to be able to talk about things that I hadn't talked about before."
Nicole, who is back on again with her Formula One driver boyfriend Lewis Hamilton, spoke out for the first time about her battle with bulimia in an interview with Cosmopolitan in July.
"It robs you of living your life. But you can recover and you can get rid of it forever," she said. "I did it and that's why it's so important for me to share my story."
LOVE NICOLE'S SIREN STYLE? Yes, this lady knows how to power dress and here are the looks to prove it.