This was the first episode to be filmed for Season 7. That explains Mulder and Scully's limited screen appearance as both David Duchovny and Gillian Anderson had other commitments, he finishing up Return to Me (2000) and Anderson still working on The House of Mirth (2000). Vince Gilligan was forced to write an episode that didn't feature the lead characters too much. This suited Gilligan just fine as he was interested in exploring an episode told largely from the monster's point of view.
In total, David Duchovny and Gillian Anderson only spent 2 days filming this episode. Usually, it was 8 days per episode. Their stand-ins were used extensively to fill in their absence.
"Hungry" is written by series regular writer Vince Gilligan, and displays many of the hallmarks of his later series Breaking Bad (2008): the protagonists are arrogant young men with violently short tempers, a Southwestern suburban fast food joint serves as a primary setting, and dark humor results from on-screen murders.
The character Donald Edward Pankow, the first victim, is listed as "the hungry guy" in the credits.