Actress Kangana Ranaut says gaining weight for a role and doing bharatnatyam left her back severely damaged, adding that she is struggling to lose the extra kilos.The actress had to gain weight for her role as late Tamil politician J. Jayalalithaa in the biopic "Thalaivi". The dance regime was also for the film."I played the first super humangirl on Indian screen, thanks to my body a rare combination of dainty yet strong looking, in my 30's I had to gain 20 kgs for 'Thalaivi' and do Bharatnatyam, it left my back severely damaged but no bigger gratification than to play a role to perfection," Kangana tweeted along with a series of photographs showing her transformation."Journey back to my fit body wasn't easy, I feel good but even in seven months not able to achieve my earlier stamina and agility back and those last 5 kgs arnt budging, there are moments of despair and then my director Vijay sir shows me 'Thalaivi' footage and all seems fine," she added."Thalaivi" is an upcoming bilingual biopic of late Jayalalithaa. The film will trace the journey of the late leader from silver screen to politics. It is directed by AL Vijay, and also stars Arvind Swami, Prakash Raj, Madhoo and Bhagyashree.