The Madhur Bhandarkar film charts the rise and fall of fictional Bollywood actress Mahi Arora, played by Kapoor.
"I think the film is 80% based on reality," said Kapoor. "I have been watching it while dubbing for the film and I am shocked!
"After viewing this film, people will know what happens in the personal life of actresses."
According to PTI, the film is believed to have drawn on the real lives of several Bollywood actresses.
Kangana Ranaut was reportedly upset that Heroine features scenes seemingly inspired by her own life. The film's central character is seen being assaulted by her actor boyfriend. There were also suggestions that the film dealt with incidents in Manisha Koirala's life.
However, Bhandarkar has denied that the film is based on any one actress's personal life.
Kapoor took over the role from Aishwarya Rai Bachchan, who was forced to pull out of the film last year following news of her pregnancy. The Agent Vinod star said that she had no hesitation in taking on the role and was not concerned by comparisons with Rai Bachchan.
"I am glad the film finally came to me as I was keen on working with Madhur since watching Chandni Bar," she said. " I am happy I've worked with him in his best film.
"I didn't have any misgiving, nor am I wary of any comparisons. I have played the role my way; no-one has played such a role before."
Bhandarkar has said that he believes Heroine will be a career-defining role for Kapoor.
Heroine releases on September 21.