But in Spanish, it specifically says that the fat one is a man (masculine article "el" and masculine pronoun "gordo", not "gorda") and the skinny is a woman (feminine article "la" and feminine pronoun "flaca", not "flaco"). There's no way you can say that in English using only articles because they lack of gender in this language. So that's the need of using "the fat man" ("el gordo") and "the skinny lady" ("la flaca"). If the title in Spanish were "El gordo y el flaco" (both masculine) or "La gorda y la flaca" (both feminine) then it would be ok to be named as "The fat and the skinny", but it's not the case.