1200-1400 calories allotment???

Hello :)

I just purchased FB meal plan and I've calculated my calories allotment... Well the thing is that using my BMR plus my activity index, I suppose to have an intake of 1673 calories and because I want to lose weight I want to create a 500 calories deficit but in the FB meal plan minimum suggested is 1600 , so what should I do? Is anyone in the same situation? How do you manage to follow the meal plan and reduce the calories allotment to the one you desired?