It could be the way u talk abt it..
maybe ur expression, ur tone.. sounds like u were joking, sarcastic
or even pervertic. Perhaps she is already not feeling gd abt her
figure, and she felt that u were rubbing into it. Or perhaps she
duno you long enough and was shocked when u told her that she has a
gd figure? Maybe she can't accept it too?
I duno.. maybe you two dun know each other well enough. That's why
the reaction.