Nothing wrong with a thick chick. It's not my first preference, and it's definitely can be like walking on rotten ice; the scale can tip too far in the wrong direction, pretty damn quickly.
The fat white chicks I see with black guys are never thick, shapely, etc. They're just dough blobs. If it's truly about white gf=higher social status or whatever, doesn't dating a fattie negate that effect anyway? Who cares if you have a white gf if no one else would date her but you.