Users physical needs are greatly reduced or completely removed. These needs include air/breathing, sleep/rest, food, drink, bodily evacuations, shelter from environmental effects and their lack (heat/cold, dryness/wetness), etc. User is also able to stay unmoving without normal effects this would have.
Due to the effects of yellow sun radiation, Superman (DC Comics) has no need for food or sleep, though he tends to eat and sleep out of habit.
Shinigami (Death Note) have no need to eat nor sleep, but do so to enjoy the sensation and laziness. They do, however, need to use the Death Note to extend their lifespan.
Artificial Humans (Dragon Ball) like #16, #17, and #18 have an infinite energy reservoir, and thus, no need to sleep or eat.
Zetsu (Naruto) are self-sustained, as Black Zetsu is an artificial human created from Kaguya's materialized will, while White Zetsu are mutated humans. Although, White Zetsu can devour corpses to dispose of evidence.
Because Timmy Taco wished that he and Sally Sandwich (Sweet Story) would be "married forever", it made it so that neither could ever die - including immunity to the effects of starvation or thirst - the wish making sure that their marriage does not end through death due [they] part.
Gems (Steven Universe) are an alien race of functionally-immortal polymorphic Gemstones. They do not need to eat, drink, sleep or breath, and can recede into their gems should their bodies be mortally wounded to heal.
As long as the Amazons (DC Comics) stay on Themyscira, she does not require food, water or any other form of nourishment to maintain her health and vitality.