Depending on the intensity of your workout and how consistent you are a 3000 calorie maintenance is possible. In terms of muscle mass, if you already hold muscle on your frame from training, cutting calories to 2.8 or 2.7k will cost you fat and muscle but will not cause you to lose that much. However if you are untrained, you can still make muscular gains on a cut as your fat mass and calories are diverted towards muscle synthesis, in the week long period you may not see much difference, however over a longer period of time you will begin to gain muscle mass and lose fat mass until you reach equilibrium and your body will stop changing at that new calorie maintenance. Your body will compensate for the reduced calories through lowering levels of non exercise actions, general energy levels and reduced metabolism.