Yes your body has gotten use to what u have been eating.. Meaning this amount of food is now what ure body is use to..
You will have to try some thing else.. This useally works for me...
Get off your diet for about a week and eat whatever.. This throws your metabolise for a loop...
Then after a week go back to your diet...You should start back to loosing..
Your metabolize gets into a habit.. Throw it off course for a while and u should return to loosing again..
Hope this helps you.. And good luck..And dont feel guilty about cheating for a week.. You are trying to get your metabolism.... Moving again..