The 'Monuments Men' star has reportedly been given a healthy eating regime by Amal Clooney, after he gained more than a stone since they tied the knot in September 2014.
A friend said: "Amal told me there are five rules for George’s new eating regime and healthy lifestyle that should get him back in shape as quickly as possible."
The five rules include no alcohol, no fatty meat and less dairy products and Amal is hoping her husband can shed 15 pounds before the Oscars, which take place on February 22.
However, the friend also revealed that the 53-year-old actor would find the healthy eating plan "tough" because of his love of tacos.
They said: "George is a pretty disciplined guy on set but, although Amal’s new eating rules seem straightforward, he’s going to find it tough because he loves Mexican food and even binges on the fast food variety several times a week in LA."
Another pal added to the Daily Star on Sunday newspaper: "There’s nothing George likes to wolf down more than a couple of spicy fish tacos followed by a shot or two of his own tequila."
Meanwhile, the star's close friends - Rande Gerber and Cindy Crawford - are believed to be helping the 36-year-old human rights lawyer get her husband back into shape.
The source continued: "Rande and Cindy have promised Amal they’ll do everything they can to help her lick him back into some sort of shape before the Academy Awards."