Nathan Fielder says that Benny Safdie eats a ridiculous amount of food on camera, every single take
The Uncut Gems director and Oppenheimer actor basically does a mukbang every time the scenes calls for it, no matter how many takes, according to Fielder

If there’s one person in the world somehow more dedicated to realism in art—at the expense of mind, body, soul, and potentially morality—than The Rehearsal’s Nathan Fielder, it may be his future co-creator and scene partner Benny Safdie.
The two lovable oddballs (and Emma Stone) are currently working on The Curse, an upcoming Showtime series about a couple producing a show for HGTV. While not much is known about the actual plot of the show (The Curse, that is, not the show within the show), Safdie recently revealed in a GQ profile that the series, which was born out of a “so stupid” but “really funny” bit that he and Fielder used to text each other frequently, also started its scripted life as a 30-minute comedy but eventually morphed into an hour-long comedy-drama.
This insight into the show’s behind-the-scenes gestation tracks, given the progression from hilarious (“Door city over here”) to harrowing (potentially traumatizing children for life) that The Rehearsal would prove to walk.
Oh, and here’s one more thing we’ve learned about the series via Safdie’s GQ profile: he eats a lot of real food on camera. Like… a lot.