For Maya 2016, the option is Mesh Display -> Reverse. @jose.fuentes: You can check your face normals by selecting an object and either Display -> Polygons -> Face Normals or going into Attribute Editor, picking Mesh Component Display and checking Display Normals. You need to reverse the normals of all the faces with green…
Your normals might be facing the wrong direction (maya thinks your object is backwards). Select your model, then go to Normals -> Invert Normals (in the Polygon menu set).