Bradley Cooper worried about gaining weight naturally for film

London: Actor Bradley Cooper says he had to gain weight naturally, without supplements, to portray a Navy Seal in Clint Eastwood's new movie.

The 'American Hustle' star, who plays the real-life hero Chris Kyle in 'American Sniper', said he feared his past struggles with addiction would come back to haunt him if he started popping pills, reported Contactmusic.

"I did it naturally because I've been sober for 10 years and didn't want to do anything. "I had a realistic conversation: 'Can I do this in three months naturally? Can I gain 30 pounds of muscle?' I didn't know if I would be able to do it or not. Thank God, luckily, my body reacted fast," he said.