It's funny, I just watched the film and I didn't feel that they made fun of the larger girl at all. SHE was the one who wanted to go on a crash diet, one of the other girls suggested that she just get a bigger dress. Yes, her dress split during the wedding, but I thought using kilt pins to pin it made it look rather fashionable (it worked for Liz Hurley.) I'm not saying it was a good movie, just that they really didn't make fun of the bridesmaid.

I thought the "fat" jokes were much worse in Love, Actually.