An organism's diet referred to what forms of food it chose to eat. Forms of diet included herbivore and carnivore.
Carnivores were flesh-eaters. They included non-sentients such as the krayt dragon, and the colo claw fish from Naboo, but also sentient species such as the Zabraks and the Pau'ans. Carnivorous diets were common in cold environments, due to the lack of plantlife. Carnivorous plants such as the reeksa were unusual plant species that evolved to capture and consume live prey in order to make up for the lack of nutrients in their soil.
Herbivorous lifeforms such as the bantha, the ikopi, the happabore, and the shaak all fed on plants.
Omnivores were organisms that fed on both plant and animal matter. Reeks were large, muscular omnivores native to the planet Ylesia that, while herbivorous by nature, could survive on meat. The vulptices of Crait dug the salt crust of their world for small mammals and tubers.
Some species, like certain birds on Jelucan, and the crab gliders native to the gas giant Bespin, were carrion-eaters, feeding on refuse and other decaying organic matter.
Other creatures were practitioners of geophagia, subsiding off of inorganic material. The fire rats of Mustafar were one example of this phenomenon; they were known to gnaw on the lava crystals of the hellish planet.
Some species were energy-eaters. The conduit worms fed off the electrical wiring of starships, and the mynocks absorbed electrical, stellar and electromagnetic energy using their mouths.