A few years later, director Martin Scorsese shut down production of Raging Bull (1980) for four months so De Niro could pack on 60 lbs. to play an older Jake LaMotta.

Jared Leto lost 28 lbs. to play a heroin addict in the 2000 film Requiem for a Dream.

He gained 67 lbs. to play Mark David Chapman, the man who killed John Lennon, in Chapter 27 (2007).

For Dallas Buyers Club (2013), he once again dropped weight for a role - this time 30 lbs. to play an AIDS-positive transgender woman.

Christian Bale reportedly lost 62 lbs. for the 2004 film The Machinist, reducing his weight to 120 lbs.

After filming the Dark Knight franchise, Bale reportedly went from 185 to 228 lbs. for the 2013 film American Hustle.

Renée Zellweger put on 20 lbs. for her lead role in Bridget Jones's Diary (2001), going from a size 4 to a size 14.

To prepare for her role as Roxie Heart in Chicago (2003), the 5'4 actress dropped back down to a svelte size 6.

Matt Damon reportedly lost 40 lbs. in just 100 days for his role as a soldier addicted to opiates in Courage Under Fire (1996). The weight loss caused so much stress on his adrenal gland that he took medication to correct it for more than a year after filming.

For The Informant (2009), he packed on 30 lbs. via junk food to play a corporate whistleblower.

He then bulked up with solid muscle for his role in Elysium (2013).

Tom Hanks lost 30 lbs. to play a dying man with AIDS in Philadelphia (1993).

He then put on 30 lbs. to play an aging baseball star in A League of Their Own (1994).
For Castaway (2000), he reportedly gained and then lost a total of 50 lbs.