Hi there and thanks for your question.
175 calories a day sounds about right for a 6-7lb cat so this would not be enough food to sustain her and could explain why she is so hungry.
If she is a very large breed like a Maine Coon, this could be why she is so large.
However, if she is obese, this is a different thing entirely.
- Go to her vet for a Body Condition Score assessment to determine what her ideal weight is and to get her started on an appropriate feeding plan
- Start a diet food (such as Royal Canin Satiety) and weigh out her portions on a scales each day
- Ensure she is not getting any treats, tit bits or human food
- Encourage exercise with e.g. laser chasers, wind up mice, a cat tree, a cat wheel etc.