In actual fact, he lost three and a half stone (52lbs) for the role, claiming the substantial weight loss almost turned into a “disorder.”
Speaking on this further, he told Kimmel: “It was difficult at times but then there’s something very empowering about it as well.
“I think just having that level of control over yourself is something - I don’t know…
“In the beginning, you’re exhausted - you sometimes you look at a flight of stairs and it takes 30 seconds to talk yourself into it.
“‘I can do this, I know I can do it…’ but once you reach your target weight you suddenly feel energised and excited.”
Phoenix also revealed how much of a strain losing weight took on his social life, as he still wanted to eat but had to isolate himself to stay away from it.
He added: “It’s tough because you can’t watch TV because a commercial comes on for food which is f****** maddening.
“It rears its head in strange ways - in dreams and stuff like that… it’s the worst.
“You don’t socialise, at all, because you don’t realise that food and drink is what all of our social activity revolves around.
“So without that, it’s like ‘What do the f*** we do? I don’t want to talk to you!’ It’s the worst.”
According to Phoenix’s interview with AP, however, the fasting was necessary in order for him to carry out the Joker’s mannerisms in the way he and director Todd Phillips envisaged.
He said: “But I think the interesting thing for me is what I had expected and anticipated with the weight loss was these feelings of dissatisfaction, hunger, a certain kind of vulnerability and a weakness.
“But what I didn't anticipate was this feeling of kind of fluidity that I felt physically.
“I felt like I could move my body in ways that I hadn't been able to before.
"I think that really lent itself to some of the physical movement that started to emerge as an important part of the character."
https://www.express.co.uk/entertainment/films/1185707/joker-transformation-how-much-weight-did-joaquin-phoenix-lose-for-joker-movie
Speaking on this further, he told Kimmel: “It was difficult at times but then there’s something very empowering about it as well.
“I think just having that level of control over yourself is something - I don’t know…
“In the beginning, you’re exhausted - you sometimes you look at a flight of stairs and it takes 30 seconds to talk yourself into it.
“‘I can do this, I know I can do it…’ but once you reach your target weight you suddenly feel energised and excited.”
Phoenix also revealed how much of a strain losing weight took on his social life, as he still wanted to eat but had to isolate himself to stay away from it.
He added: “It’s tough because you can’t watch TV because a commercial comes on for food which is f****** maddening.
“It rears its head in strange ways - in dreams and stuff like that… it’s the worst.
“You don’t socialise, at all, because you don’t realise that food and drink is what all of our social activity revolves around.
“So without that, it’s like ‘What do the f*** we do? I don’t want to talk to you!’ It’s the worst.”
According to Phoenix’s interview with AP, however, the fasting was necessary in order for him to carry out the Joker’s mannerisms in the way he and director Todd Phillips envisaged.
He said: “But I think the interesting thing for me is what I had expected and anticipated with the weight loss was these feelings of dissatisfaction, hunger, a certain kind of vulnerability and a weakness.
“But what I didn't anticipate was this feeling of kind of fluidity that I felt physically.
“I felt like I could move my body in ways that I hadn't been able to before.
"I think that really lent itself to some of the physical movement that started to emerge as an important part of the character."
https://www.express.co.uk/entertainment/films/1185707/joker-transformation-how-much-weight-did-joaquin-phoenix-lose-for-joker-movie