Aamir Khan on the heavy decisions he took while filming Dangal

Aamir Khan tells a press conference in Dubai how he put on – and then lost – 27 kilos for his latest film Dangal. Satish Kumar / The National

Aamir Khan's new film Dangal is a weighty biopic in more ways than one. One of Bollywood's most acclaimed actors, he put on a staggering 27 kilograms to play the role of former wrestler Mahavir Singh – then shed it all in just five months to shoot scenes of a younger, fitter version of the character during his wrestling heyday.

Dangal, which is now showing at UAE cinemas, tells the moving true story of how, lacking a male heir to follow in his footsteps, Singh trains his daughters, Geeta Phogat (Fatima Sana Shaikh) and Babita Kumari (Sanya Malhotra), to become wrestlers.

The stars visited Dubai recently to discuss their experiences making the film.

Khan revealed he took a sweet route to pile on the weight.

“I just went to town eating stuff normally I’m not supposed to,” he says. “My mother’s cooking is very good so I made full use of that, and samosas – all the deep-fried stuff.

“Suddenly my body got a shock, my organs were working with 27 kilos more overnight. Usually you put on that much weight over 20 years.”

Losing all that weight in just five months was, Khan admits, quite a challenge, which he tackled by following a healthy, balanced diet. He refutes rumours on social media that he resorted to steroids.

“I followed a really strict diet, and I worked out really hard,” he says. “I was really frightened, to be honest, when I started this process. I thought I was never going to get there. I was really fat.

“I realised I could not look at the end goal, because then you get disheartened. Instead, you have to look at what you can do today. You think one day at a time, and then you realise you’re nearer your destination.”

The filming of Dangal was a gruelling physical challenge, and at first Khan wondered whether his two young co-stars, Shaikh and Malhotra, both of whom are making their movie debuts, would be able to cope. He is full of praise for their focus and tenacity.

“I’ve been working for 27 years now and they, on their first film, were 10 steps ahead of me in every scene,” says Khan. “These girls are very magical, you’ll see it in the film.”

Khan knew he had to make Dangal as soon as he was shown the script by the film's writer and director, Nitesh Tiwari, three years ago. "I asked, can you guys wait for a bit? Maybe five or 10 years?" says the actor. "I felt that in PK [Khan's 2014 satirical sci-fi comedy], I was playing this young man and I didn't know how people would react to me suddenly jumping to 55, fat and grey-haired. That could be the end of my career. It was too close to my real age."

However, Khan couldn’t get the script out of his head. “It had got under my skin, so I decided to put aside my stupid thoughts of stupid fears and just do it,” he says.

Some might suggest that the timing of the film's release may not be ideal, as Dangal arrives in cinemas just five months after Salman Khan's Sultan, which is also about female wrestlers, and after a string of recent Bollywood biopics, including the cricketing double of M S Dhoni: The Untold Story and Azhar.

Khan says the film is about more than just the sporting action, however.

“It’s actually a story about India, which is why its special,” he says. “The story of Mahavir, how he stood by what he believed in and how he fought and how he got his kids to fight, is very inspiring.”

Khan believes that a film with such strong female leads will help promote female empowerment in India.

“There is a certain mindset that we would like to change,” says Khan. “It doesn’t happen overnight, it happens gradually over time, and each opportunity to change a mindset contributes something to it – it could be a film, a television show or newspaper articles. Slowly, you are able to make people look at things differently.”

Khan has yet to make a film in the UAE, but says he would love to. “Dubai is a beautiful place, and I’m sure it’s a wonderful place to live – a lot of my friends live here,” he says. “I’d love to come here and stay longer and shoot a film here, but it would depend on the creative requirement of the script. As soon as I get a script that I think needs to be shot here, I’d love to come.”

• Dangal is in cinemas now