Hm how old is she? Sometimes as cats get older they just need less food to maintain their weight, just like humans. Do you know how many calories are in that cup of food? Chances are it's too much. You'd be surprised how little food cats actually need but this greatly depends on the calorie content. You can check the bag or do a quick Google search to get the amount of calories per cup. Was she spayed recently? That also decreases the amount of food they need to maintain their weight. I can help calculate how many calories she needs a day based on her weight, age and whether she's spayed or not. Cats also sometimes just have a "fat pad" underneath their belly that kind of sways and hangs down lol. My vet said that this is normal because of how sedentary house cats usually are.
