Why weren't there any women in the fight club?

Women probably WERE in Fight Club, but in support roles, like manning the kitchen for hungry fighters.

The narrator clearly says near the beginning to Marla that it is a mens only club.

The film is a parody of masculinity that shows how some men express their masculinity in a toxic way because they feel victimized, and the fact that women wren't allowed (or at least it is implied that they weren't) just helps drive this message.

This was by no means an anti woman film. It definitely showed irritation to feminine stuffs like decor,baby pampering..but by no way a chauvinist film. The protagonist was absolutely pissed off with his father the way I saw it. Wanted bonding with fellow men, which he lacked growing up. By no means did this film throw dirt at women.

Also wanted to mention, I go to a mixed martial arts class where 40 girls have their noses broken another 20 has other bones broken. Martial arts and athletism among girls are not too common. But we DO EXIST in this same planet. (And yes the black belters sometimes beat the *beep* out of the guys who spar. Sometimes 4 at a time here.)