The 53-year-old rocker was both fascinated and horrified by what he witnessed in Asif Kapadia's 2015 film, as he watched the drug-addicted musician turn from a ''joyous person'' to a lost soul who was ''trying to escape'' her life.
Hetfield decided to detail his feelings about the 'Rehab' singer in the track 'Moth Into The Flame' from 'Hardwired... to Self-Destruct'.
Speaking on Canadian radio station 102.1 The Edge, he said: ''Just watching that movie was extremely saddening - how her life went from such a lively joyous person, to someone who was just trying to escape the reality of where she was.
''It really hit me in the one part of the movie where she was lost in her mind, it seemed, and she was just leaving her flat in England. The press were just hanging out in front of her place all the time, snapping these pictures of her, saying, 'Hey, Amy, how's it going?' Talking to her like they know her. They just don't notice - they wouldn't say, 'You look skinny, you look unhealthy.' There was a total misconnection there with reality.''
Winehouse tragically died in July 2011 at the age of 27 from alcohol poisoning after a heavy drinking binge.
'Hardwired... To Self-Destruct' is Metallica's 10th studio album and their first since 2008's 'Death Magnetic' and Hetfield previously revealed a lot of the tracks on the LP were influenced in some way by Winehouse.
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