Saiyans (サイヤ人, Saiya-jin) are an endangered race of extraterrestrials in the anime and manga Dragon Ball and its sequels, Dragon Ball Z and Dragon Ball GT. In the series, the Saiyans are a naturally aggressive warrior race who were supposedly the strongest warriors in the universe. Nearly all of the Saiyans were obliterated by Frieza. The Saiyans play a central role in Dragon Ball Z and Dragon Ball GT once it is revealed that the protagonist, Goku, is actually a Saiyan sent to destroy Planet Earth.
Saiyans are able to eat far more than an average Human being. Saiyans eat lots of food because they are built for fighting and therefore need a lot of energy. Most Saiyans can eat more than physicaly possible. This is first demonstrated by Goku in Dragon Ball.