It seems to be mainly the older women, but I've noticed that a few of the social groups that I go to (there are a lot of older women there) seem horrified when asked to pick their three course lunch for Christmas at a local restaurant. They are fine with starters, but a lot of them say things like "I couldn't eat dessert as well, it would be too much for me" in a really judgy tone. The best one was from one of the women who is about 20 stone saying she couldn't eat a two or three course meal 
I don't know if it's because women are supposed to be seen as dainty and ladylike and not have big appetites, but it just comes across as so smug.
AIBU to think that some women are really smug about the whole cake/dessert thing?