Why do women love overweight guys?

I was talking to a friend and he told me that a woman he knows (who is kind of fat) loves a very overweight guy. He’s so overweight that he can’t even walk properly. I’m just trying to understand why she would love this guy. Is it because she is also overweight? I’ve seen a lot of overweight women together, but I don’t understand the psychology behind it. Is there a psychological term for this kind of attraction?