She is happier, too, now that she is no longer responsible for killing animals, said a report on Tuesday.
But the recent change in diet has her parents worried she is becoming too thin, Kapoor told a newspaper.
"It's true that I used to love non-vegetarian food," the paper quoted her as saying.
"But I feel good that I am not killing any animals these days," Kareena said.
Kapoor believes vegetarianism makes for healthier living, but her father, former actor Randhir Kapoor, does not buy the argument. Dismayed that small portions of lentils and flat Indian bread have replaced chicken and seafood, he regularly asks why she is not eating any more, she said.
Her most recent hit was Omkara a Bollywood version of Shakespeare's Othello.