Jared Leto suffered with gout after putting on weight for 'Chapter 27'.
The 42-year-old actor had to gain 67 lbs for his role of Mark Chapman - the deranged fan who assassinated John Lennon - in the 2007 biopic, but he has vowed never to pile on the pounds for a movie again because he doesn't want to put his health in jeopardy.
He told The Guardian newspaper: "Really, it's a stupid thing to do. I got gout, and my cholesterol went up so fast in such a short time that my doctors wanted to put me on Lipitor, which is for much, much older people. Again, though, a fascinating journey.
"I had some reservations because I love everything John Lennon ever did. But in the end I wanted to explore a specimen embodying the total failure of humanity, just walk down this brutal path again."
However, the 30 Seconds To Mars singer - who has been nominated for the Best Supporting Actor Oscar for his performance in 'Dallas Buyers Club' - didn't have too much trouble trying to shift the extra pounds as his active lifestyle on tour with his rock band helped him shrink back to his previous weight.
He explained: "I lost a lot of it by going on your, not straight away, but I was still kinda waddling around on stage for the first few dates, and eventually it came back off, thank God."

Justin Bieber searched for spiritual help this weekend which he hoped to achieve through a baptism-like ceremony.
The 19-year-old singer was keen to find a Manhattan property with a private pool on Saturday (01.02.14) to conduct a "cleansing ritual" with the Hillsong Church NYC which believes a person should seek baptism in the Holy Spirit to live a fruitful Christian life.
A source told the New York Post newspaper: "Justin and his team spent time on Saturday searching for a place with a pool where they could conduct a baptism for him, a cleansing ritual, with the Hillsong Church. But they couldn't find a place in time."
This comes after Justin made headlines for getting himself in trouble.
The 'Confident' hitmaker is facing legal problems in Toronto for allegedly assaulting a limo driver, he allegedly egged a neighbour's house in Los Angeles and was arrested for driving under the influence (DUI), resisting arrest and driving without a licence in Miami.
Another source added: "Justin is serious about his Christian faith, and after recent events, he needed to take a pause."
Justin is believed to have been baptised as a child and is known to be a fan of the megachurch - which is a Protestant church that has more than 2,000 persons in average weekend attendance.

Arctic Monkeys will headline this year's Reading and Leeds Festivals.
The band - which includes frontman Alex Turner, guitarist Jamie Cook, drummer Matt Helders and bassist Nick O'Malley - are returning to the event after they topped the bill in 2009 and will play on the main stage at both sites for the UK festival which is scheduled between August 22-24.
They confirmed the news on their website, writing: "Arctic Monkeys are pleased to announce they will be headlining Reading and Leeds Festival 2014."
It was previously revealed Blink 182, who headlined in 2010, will play their only UK gigs at the two venues next year.
Bassist Mark Hoppus said last year: "[The new] year will see us in the studio preparing new music, getting ready to rock the fine people of the UK."
Singer/songwriter Jake Bugg will make his debut on the main stage at the event, while dance music duo Disclosure and metal band Of Mice and Men will also play at the festival.
Indie band Metronomy, US band Warpaint with Pusha T, Royal Blood, The 1975, and rap collection I Am Legion have also been announced as part of the line-up.

Britain's Queen Elizabeth will mark the 70th anniversary of the D-Day Landings by a visit to France this June.
The 87-year-old monarch and Prince Philip will attend events in Normandy to commemorate June 6, 1944 when the Western Allied forces initiated an operation to liberate mainland Europe from Nazi occupation during World War II.
The royal couple will be guests of President Francois Holland - who the queen has not officially met before - at the Elysee Palace in Paris.
The queen's communications secretary said in a statement issued by Buckingham Palace: "Her Majesty and His Royal Highness are visiting at the invitation of the President of France, President Hollande."
The queen served as a mechanic in the Auxiliary Transport Service during the war while the prince was lieutenant in the British navy.
Elizabeth's last state visit to France was in 2004, which is the same year she attended the 60th anniversary of the D-Day landings in Normandy.
The last official state visit by a French President to the UK was by Nicolas Sarkozy and his wife Carla Bruni in 2008.

Blondie are set to receive the NME Godlike Genius Award.
The 'One Way Or Another' hitmakers will be recognised for their musical genius at the NME Awards 2014 with Austin, Texas on Wednesday, February 26.
The iconic band, fronted by Debbie Harry, have confirmed they will pick up their prize in person and perform at the event, held at the O2 Academy in Brixton, and it's the first time a female performer has won the accolade.
Blondie said: "We've always had a special relationship with the UK and this is great, it's nice to be recognised and it's an outstanding list. To be honoured so nicely, and to play music. What could be better?"
The punk group from New York City are celebrating their 40th anniversary with a two-disc release, 'Blondie 4(0) Ever', comprising a greatest hits album and a new record, 'Ghosts of Download', in May 2014.
NME's Editor Mike Williams said: "As they celebrate their 40th anniversary, there could be no other band more worthy of being honoured as NME's Godlike Genius 2014 than Blondie. They re-wrote the rulebook in the late 70s by dragging punk rock to the top of the charts, and their classic songs still sounds as fresh as ever today.
"Everyone from Iggy Pop, Lily Allen, Lady Gaga and Julian Casablancas have looked to Debbie Harry for inspiration - she's the most iconic frontwoman rock'n'roll has ever produced. It goes without saying that NME is hugely proud, not to mention extremely excited, to be honouring her and Blondie with our most coveted award in 2014."
Previous winners include The Clash, Paul Weller, The Cure, Manic Street Preachers, New Order & Joy Division, Dave Grohl, Noel Gallagher and last year's champion Johnny Marr.

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Bono thinks U2 are becoming irrelevant.
The 'Invisible' rocker admitted that it has become harder for his band to remain significant in the music industry as they grow older, because the personal experiences they depict in their songs may no longer connect with a mainstream audience.
Speaking during an interview on BBC Radio 1, frontman Bono told Zane Lowe: "We're on the verge of irrelevance. You have to make stuff relevant to you and where you're at, make an honest account of what you're going through. If that's relevant to other people, great. But we don't know."
The singer also spoke about the inspiration behind the band's as-yet-untitled 13th studio album, which he claims harks back to when the group - including The Edge, 52, Adam Clayton, 53, and Larry Mullen, Jr., 52, - first got together in 1976.
Bono, 53, explained: "We went back to why we wanted to be in a band in the first place. We were listening to the Ramones and Kraftwerk - you can hear both on 'Invisible'. It opened up a whole valve for me writing, it was like a damburst of sorts. "
Bono says the record won't be finished for another two months, but once it's complete the group are looking forward to playing the new tracks in smaller venues.
He explained: "For this album, we're going to start indoors. We'd like to play the O2 [arena]. Sometimes it's nice to play intimate things like that."

Joe McElderry was crowned winner of 'The Jump' last night (03.02.14).
The former 'X Factor' star - who replaced Henry Conway in Channel 4's winter sports competition - was delighted that he managed to pull off a 17.5m jump from a 40m ski ramp, beating Donal MacIntyre who only managed 13.5m.
Following his win he gushed: "I have had an absolute blast. We've had so much fun."
Finalists Sir Steve Redgrave and Marcus Brigstocke pulled out of the competition following injuries.
The Olympic champion who had bruised his ribs during a fall and broke a bone in his hand while competing on the show, was "absolutely gutted" he couldn't continue.
The five-time gold medallist explained: "I'm absolutely gutted. I love skiing, I love the show. I wanted to give it my all and unfortunately I gave it too much three days ago and that was it. It's not the not winning, it's the not completing it."
Marcus admitted he'd had a great time on 'The Jump' but injured himself when he landed on his left knee during the ski cross competition and was taken to hospital.
He added: "I've had the time of my life. My aim was to do everything and I'm dead proud. I came on the jump and never jumped!"

Peter Andre and Gary Barlow have exchanged parenting tips.
The 40-year-old singer - who already has Junior, eight, and Princess, six, with ex-wife Katie Price and three-week-old daughter Amelia with fiancé Emily MacDonagh - admitted him and the 'X Factor' judge found there is "no right and wrong way" to raise children.
He told the Daily Mirror newspaper: "I had this chat with Gary Barlow - he won Father of the Year last year and I had it the two years before.
"We discussed what makes a good parent, and the answer is simple, no one does it the right or wrong way, you put your kids first, you're a good parent. I'm much easier and more lenient with my kids than my parents were with me, but it doesn't make me a worse parent, it's my way.
"Before he won, Gary said 'I'm taking it off you this year, Andre'. I said I'd let him have it, maybe I need to give my arm a rest."
Peter - who proposed to Emily on New Year's Eve after 18 months together - is delighted with what his life has to offer him at the moment and is looking forward to the future
He gushed: "I have the wonderful gift of a baby, the engagement, and to have this as well, a career thing. It's unbelievable."

Mary Berry isn't nervous about 'The Great British Bake Off' moving to BBC One.
The hit reality competition - which drew some nine million viewers last year - will switch from BBC Two for its fifth series later this year and judge Mary, 78, insists there is no pressure to change the show ahead of its big move.
She told BANG Showbiz exclusively: "I'm not at all nervous about it. The programme is going to be just the same, and we'll put just as much into it. The bakers won't change, we won't change - the standards will be the same. It'll all be great fun."
Meanwhile, series four runner-up Kimberley Wilson - who lost out to Frances Quinn in the final last year - says the contestants on the show really did get along and admits people are surprised by the harmony amongst them.
She revealed: "When people stop us they always ask, 'Is it real? Do you really get on?' We absolutely do.
"We're trying to organise reunions, but people are a bit busy at the moment, but we do want to get together. You're in this incredibly intense environment and you feel bonds really quickly."

Woody Allen's lawyer has blamed a "vengeful lover" for Dylan Farrow's sexual abuse claims.
The 'Blue Jasmine' director's adopted daughter wrote an open letter for the New York Times at the weekend - in which she made a series of accusations about the filmmaker abusing her at the age of seven - and his legal representative Alkan Abramowitz appears to have suggested Dylan's mother, Woody's former partner Mia Farrow, made up the accusations.
Alkan told CNN: "It is tragic that after 20 years a story engineered by a vengeful lover resurfaces, even though it was fully vetted and rejected by independent authorities.
"The one to blame for Dylan's distress is neither Dylan nor Woody Allen."
The accusations date back to 1992, when it emerged Woody was having an affair with Mia's adopted daughter Soon-Yi Previn, who he later married.
In the custody battle over the estranged couple's children, Dylan, Moses and Ronan, the actress alleged the filmmaker had molested their daughter but the charges were later dropped.
Following the publication of Dylan's essay, the 'Midnight in Paris' filmmaker slammed her claims as "disgraceful".
His representative said: "Mr. Allen has read the article and found it untrue and disgraceful. He will be responding very soon."