Less calories than what you're supposed to eat?

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My progress has slowed down; I've been told that it might be because my calorie instake was too low sometimes that now my body's gotten used to it.
So I'm trying to use all the 1200 Kcalories I have for now (even when I'm not hungry) to be able to cut it down and help the progress work. I just dunno if I'm doing the right thing or not.