should I switch to maintenence calories?

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I set my goal at 1300 (ish) cals daily and decided to try it for the month. I seem to be maintaining. I had a thought, when I signed up, that because I am used to eating only 1000 cals a day (but living a sedentary lifestyle) that getting fit would only require 1300. Now I am slowly building muscle, which was my goal, and am losing inches but mantaining my 98 pounds.

I guess my question is, if I switched to maintenence would I be chronically under? would I gain fat? or am I hampering my muscle definition by only eating 1300.

I sort of thought that I only had to eat that much because of my very small frame, but as I switch to healthy foods that count, I find myself getting hungrier and actually having to do without. it's a strange feeling!

Thanks!