But why does he do it? Is it some sort of weird method acting tactic, or is he always just a bit peckish on set? Well, it turns out it's kind of neither. And both.
In an interview with JOE while on the promo circuit for the latest Tarantino flick, Pitt and his co-star Margot Robbie were asked about a 15-minute compilation of the actor chowing down on snacks, and whether or not they'd seen it.
Robbie said she hadn't, but had noticed he eats food 'a lot in movies'.
Pitt then chipped in: "I like to busy myself, I'm a grazer by nature, so..."
Hey, we can all relate.
Robbie asked her fellow actor: "In Ocean's Eleven, do you talk about it, or do you just always have food handy?"
Pitt replied: "We just had it - well, there was actually method to that, because he was always on the run, always on the move, I figured he could never sit down and have a proper meal. So he always had to grab something on the run."
But it gets better, because one absolute genius on Reddit (where they're always found loitering) has even managed to find a correlation between the amount Pitt eats in movies and the average audience/critic rating and box office takings - claiming the more he chomps, the better the film does.
As a quick disclaimer u/LundgrensFrontKick wrote: "I am not implying direct correlation equals causation. I'm just presenting random data in hopes of making a few people chuckle. Hopefully this data won't be too much to digest."
They wrote: "I decided to do a rewatch of his movies to put together a master list of all the food, and see if any cool statistics popped out."
And it turned out that some pretty cool stats did pop out.
Brad Pitt movies featuring no eating:
Tomatometer Average - 64%
IMDb User Score - 6.9
Domesitc Box Office Average - $68 million (£56m)
Brad Pitt movies featuring him eating 1-200 calories
Tomatometer Average - 61%
IMDb User Score - 6.8
Domestic Box Office Average - $110 million (£90m)
Brad Pitt movies featuring him eating 200+ calories
Tomatometer Average - 67%
IMDb User Score - 7.0
Domestic Box Office Average - $143 million (£117m)
So there you have it: get Brad Pitt to have a snack while filming your movie and it'll bang.
Well, maybe - but I'm personally going to use this as firm enough evidence to justify eating crumpets, Hula Hoops and Jammie Dodgers all day at my desk.