John Goodman, 63, revealed a shocking weight loss at the "Trumbo" London premiere Thursday night. 

The "Monuments Men" actor has spoken about his struggles with weight in the past, revealing he once weighed 400 pounds, according to ABC News. Through diet and exercise Goodman lost more than 100 pounds.

The "Roseanne" star has had an open and public battle with his weight, noted The Daily Mail. In 2010 he spoke publicly about his health struggles.

"I'd lose 60 pounds every spring, and then I got too fond of the barley corn and I'd just start missing it too much," Goodman told David Letterman on "The Late Show," according to MSN News.

The actor's weight loss is evident when comparing a November 2014 photo at the premiere of "The Gambler" to Thursday night's premiere of "Trumbo." See the photos below.

Goodman said returning to theater motivated him to get in shape.

"You have an adrenaline rush and once that's over, you find yourself, at the end of the evening, spent," MSN News reported.

Goodman's latest film "Trumbo" about a successful Hollywood screenwriter is scheduled to be released on Nov. 6.