"I was wondering, 'How is he doing it? How is he doing it so fast?' and then he's like, 'I just eat Haagen-Dazs or ice cream or whatever,'" Reilly recounted. "I was like, 'But how can you eat that much ice cream in a day without getting a freeze headache?' And without missing a beat, he was like, 'Oh, I just warm it up and just drink it.'"
"In the microwave," Farrell added. "I was always a better drinker than an eater so I just applied that rule!"
Farrell, who said that the high-fat diet was only fun "for about two days," said that his health -- especially his sleep schedule -- suffered quite a bit.
Now, Farrell appears to be back in tip-top shape, and his method for losing all the extra pounds was apparently very straightforward: "I dropped the weight so quickly just by starving and working out," he explained.
In The Lobster, Farrell plays David, a newly-single introvert who, according to the rules of society, must find love within 45 days or he'll be turned into an animal of his choice -- which happens to be the eponymous lobster.
The surreal comedy, which also stars Rachel Weisz and Ben Wishaw, hits theaters Friday.