Is this a normal thing for her or something she just started? I would watch for any signs of health problems. If she isn't very active than perhaps she is just not hungry enough to eat all you give her, and if she is very active than her weight sounds normal and I wouldn't worry. You wouldn't believe how many dogs at the park by us look almost emaciated just because they are so active. They are otherwise in good health. As long as she isn't showing signs of a health problem I would be happy for her, my Autumn is 10 pounds overweight and is shows healthwise. What type of food do you feed her?