The 34-year-old said Springsteen's jeans were "very snug" and revealed the Born In The USA singer visited the set of the biopic, in an interview with actress Kate Hudson for US outlet Variety.
Asked how it felt to wear Springsteen's clothes, White said: "I felt like I had to stop eating. It was all really helpful - the boots, the jeans, the jackets.
"It was tight and really informed the physicality. It messed with my posture. Bruce also gave us clothing he wore as a young man, some of his actual pieces...
"I haven't talked about this yet because it feels so precious, but he did give me his St Christopher medal that he had for a very long time, and he gave me a guitar to learn to play, a 1955 Gibson J 200."
Hudson, who is also due to star in a music film in Song Sung Blue, which sees her play Claire Sardina, a member of Neil Diamond tribute band Lightning And Thunder, revealed she also had the same guitar, calling it "my favourite".
She also asked White how involved Springsteen was in the film, to which he replied: "Bruce gave the go-ahead for our director, Scott Cooper, to do this movie but was hands-off during the writing process.
"I got together with him first in London, at Wembley, I got invited to sound check. He brought me up on stage prior to everybody coming in.
"We spent a few weeks together and then he was on set all the time, which was not something that we knew going into it."
When asked how he felt taking on the musical side of the film, White said he was "in luck, because there were very few chords used" on Springsteen's 1982 album Nebraska, which is covered in the film.
White added: "He's so honest in all of his music, there's so much specificity in his writing. The canvas of Nebraska is so rich with himself and his experience. It was like I had a map."
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