The fat sand rat (Psammomys obesus) is a terrestrial mammal from the gerbil subfamily that is mostly found in North Africa and the Middle East, ranging from Mauritania to the Arabian Peninsula. This species usually lives in sandy deserts, but may also be found in rocky terrain or saline marsh areas. Fat sand rats are very selective in their diet, only eating stems and leaves of plants from the family Amaranthaceae, more commonly known as the amaranth family. The fat sand rat acquired its name due to the fact that when it is fed a typical rodent diet, it quickly becomes obese and develops diabetes. P. obesus has an average lifespan of 14 months in the wild and 3-4 years in captivity.