Gordo means fat in Spanish as an adjective.If you are talking about fat as a noun, than it would be grasa.
No gordo
Gordo
su grasa
dedo gordo
cordo fue
estas gordo [thats a really mean thing to say] lol
You're not fat = Tu no eres gordo/a (male/female)
You would say "guapa pero gorda".
que es la grasa
me estoy poniendo gordo
El chico es gordo