Hollywood transformations are always mind-blowing whether it be with the help of prosthetics, CGI, or many hours in the gym.
For this list of 20 transformations we look at stars who took on the task of changing their body for a role.
Like Hugh Jackman who got absolutely shredded to play the lead in 2013's The Wolverine with the help of a diet recommended by Dwayne 'The Rock' Johnson which required him to eat 6000 calories a day.
Hilary Swank got into boxing shape for 2004's Million Dollar Baby and landed an Oscar for her dedication, while Jake Gyllenhaal went from skinny in Nightcrawler (2014) to swole in Southpaw (2015). Impressive!
View the full list above.